GEOFF BENNETT: Health care costs are climbing, putting new pressure on millions of Americans and raising questions about the coverage they can afford.

According to KFF -- that's a health policy research organization -- premiums for employer-sponsored family health insurance rose 9 percent this year, with the average annual cost now exceeding $7,000 for workers.

And the challenges extend to Medicare Advantage, the private insurance plan that more than 30 million Americans choose as an alternative to traditional Medicare.

With Medicare's annual open enrollment period now under way, seniors are weighing their options.

But in some parts of the country, insurers are pulling out of markets or eliminating plans that Americans have come to rely on.

We spoke with several seniors struggling to navigate those changes and an increasingly complicated health care system.

SUSAN HAYSE, Medicare Advantage Customer: I'm Susan Hayse, and I have been on the Medicare Advantage program for four years.

BOB HEFFERNAN: Medicare Beneficiary: I'm Bob Heffernan in Vermont, and I was on the Medicare Advantage plan, actually two of them for three years, and when they both withdrew from that system, I switched back successfully to original Medicare.

DIANE PAYNE, Medicare Advantage Customer: I'm Diane Payne.

And my biggest challenge for picking a plan next year is the cost of dental plans and vision are going up.

Deductibles are going -- out of pocket is going up.

And I just want to try to get the best deal for what I'm paying for.

BOB HEFFERNAN: Medicare Advantage was truly superior, in my view, to original Medicare.

It covered the doctor's visits, the lab costs, the prescription drugs, the hospital expenses.

And now I don't have the option to go to Medicare Advantage again because they basically have left the state of Vermont.

DIANE PAYNE: I realized last November that I got diagnosed with breast cancer and I had an agent come to the house to talk to me.

It was hard to figure out what to do.

SUSAN HAYSE: This particular year, it was a big shock.

Every year, you get the notification from your insurance company that there's going to be changes to your policies.

There were things that had copies that were dollar amounts, like $50, changing to 50 percent.

DIANE PAYNE: I saw that chronic illnesses and things like cancer can impact, even on our Advantage plans, how much you're going to pay per office call and visit.

Oh, I'd like to know what I might be getting into.

Am I going to be charged more?

Am I still going to be able to see my oncologist?

SUSAN HAYSE: I have developed a condition that will probably keep me from being able to switch back to original Medicare and a supplemental policy, or it'll be exorbitantly expensive.

BOB HEFFERNAN: Now, of course, we're back to paying for Medigap, which is expensive, and paying for prescription job coverage, which is expensive, and paying for the eye doctor and paying for the dentist.

DIANE PAYNE: Because of the chemo and the radiation, suddenly, dental is really important to me.

And if they're just going to cover the checkups and not cover fillings or any problems, and they cut it, my current plan, I started looking elsewhere.

BOB HEFFERNAN: They all have deductibles now.

So I'm not even adding that in that you're paying up until you hit a deductible, that you have to pay out of pocket before they will even start covering.

SUSAN HAYSE: If I'm unable to switch to original Medicare and a supplemental program because of a preexisting condition, I will switch to a different Advantage program that aligns more closely with the medical network I prefer here in my area.

DIANE PAYNE: It's a legwork for something that should be much simpler.

Just tell us.

Just put it on your plan and just say what will cost.

GEOFF BENNETT: Lots to discuss.

Luckily, we have with us Dan Weissmann, creator and host of the health care podcast "An Arm and a Leg."

It's great to speak with you.

So your team recently examined the changes sweeping through Medicare Advantage.

What did you find?

What accounts for all of these changes and, in some cases, insurance companies dropping the plans that seniors have come to rely on?

DAN WEISSMANN, Host, "An Arm and a Leg": Yes.

And there's no single answer to it, except the biggest picture one, which is the insurance companies are private companies, they're responsible to shareholders, and they have been deciding in a lot of cases these plans that we're offering, it's not going to make us enough money, so we're not going to offer it any more, or we're going to change the terms to be more advantageous to us and less advantageous to you.

GEOFF BENNETT: And for folks who have not yet had to rely on these programs, we should explain or you should explain, what's the difference between Medicare and Medicare Advantage?

DAN WEISSMANN: Traditional Medicare, as people call it, is run by the federal government.

It's kind of what we think of as Medicare.

Unless you're checking into the hospital or getting something at the pharmacy counter, everything else, physical therapy, outpatient surgery, doctor visits, traditional Medicare only covers 80 percent of the bill.

So you're left responsible for 20 percent, which can be, listen to all those things I just said, untold thousands of dollars, depending on your health.

And unlike other insurance these days, there's no out-of-pocket maximum.

So you could be on the hook for almost anything, unless you pay out of pocket for what's called a supplemental plan or a Medigap plan.

And that fills in that gap.

However, there are still some things that traditional Medicare doesn't cover at all, vision, dental, hearing.

People sometimes joke that, these are like luxury organs?

So enter Medicare Advantage.

It's run by private insurance companies.

And they will say, we're going to wrap these things all together.

We're going to give you vision, we're going to give you dental, we're going to give you hearing.

You will not be on the hook for untold amounts of money.

We're going to limit those things for you.

And one thing that comes as a big surprise to a lot of people when I started reporting on it, it was a surprise to me, is, Medicare isn't free.

You pay a premium, about $200 a month for most people to the federal government for it.

Some Medicare Advantage plans are like, we will take care of that for you.

So that is very, very attractive.

Medicare Advantage has what some people think is a downside, which is you're negotiating with a big insurance company for your health care and you're doing it on their terms.

They can tell you, nope, that doctor is not in our network, we don't pay for that.

Or, yes, you say you want that treatment, it's not on our plan.

We're not going to pay for that.

You can fight us if you want.

So these are things that many of us who are under 65 imagine -- did not imagine we would still be fighting over when we got to Medicare, but it is part of Medicare Advantage.

GEOFF BENNETT: For someone who decides that Medicare Advantage is no longer right for them, how easy is it to switch back to traditional Medicare?

Are there financial or coverage obstacles they might not anticipate?

DAN WEISSMANN: Yes, it can be very tough.

In some ways, you get a choice between traditional Medicare and Medicare Advantage when you first enroll in Medicare, when you're generally 65 years old.

And that is mostly a no backsies situation, except for a few states.

When you sign up for Medicare for the first time, you can get a supplemental plan if you want one afterwards.

If you want to switch back to traditional Medicare, they can refuse to cover you, the supplemental plan or a Medigap plan.

They can say, you have a preexisting condition, we don't want to sell you a policy, or we're going to adjust the price of your policy to something you can't pay.

That comes as a big surprise to a lot of people, and this is a thing, because you sign up for Medicare when you're 65, you might be like captain of the pickleball team, everything's great, never go to the doctor.

But you are signing up for Medicare Advantage for an older, perhaps sicker version of yourself.

And that's tough for a lot of people.

GEOFF BENNETT: With open enrollment under way and this December 7 deadline approaching, what should seniors be paying particular attention to?

What's the most important advice you can offer?

DAN WEISSMANN: The first is watch the mail.

If you get a letter from your insurance company saying, we're changing your plan or we're no longer offering your plan, you want to get on that right away.

And then you want to start sussing out your options.

There's kind of two big places to go.

One is Medicare itself operates a hotline.

It's like 1-800-MEDICARE.

Call.

The other is, every state has a program called SHIP.

It's an acronym, but basically, it's a federally funded program that exists to help you understand your choices with Medicare.

Nobody's earning a commission.

They're there to help you.

And to find the one in your state, the best thing to do is go to Google and type in the name of your state, the word SHIP and the word Medicare.

And it should pop right up.

You call those folks, and you want to do it as soon as possible.

In addition to a lot of plans closing this year, some carriers have asked the feds and gotten permission to cap enrollment in some plans.

So you might identify a plan and you're like, that's the one that I want.

And they might say, if you're late, sorry, there's no more room in that plan for you.

So you want to get on it right away.

GEOFF BENNETT: Dan Weissmann, creator and host of the podcast "An Arm and a Leg," thanks for speaking with us.

DAN WEISSMANN: Thanks so much for having me.