(MONEY Magazine) – Q My father died in March 2004. I am the executor of his estate. I thought everything was settled, but by December we started getting medical bills from Kaiser that had already been paid because they now say that my father never had Medicare Part B. I know for a fact that my father did have both parts of Medicare. The collection calls are overwhelming. The bills are approaching $60,000. What can I do? --Jennifer McGaha, Holly Springs, Ga.

ANSWER According to Medicare, a government audit last year showed that your father, Donald McClure, was not eligible for Medicare Part B. His coverage was rescinded posthumously. Then Medicare went looking to be repaid for the charges incurred during his six-month illness. Once Kaiser received what amounted to a retroactive claims denial, they passed the bills along to you.

Medicare Part B covers doctors' services and outpatient hospital care, which may sometimes be covered by employer-based insurance. While Medicare Part A (hospital coverage) typically begins automatically at age 65, you must specifically choose Medicare Part B if you need it. Most people who opt for Part B have the premiums deducted from their Social Security; others prefer to be billed directly by Medicare. To prove that your father had Part B, we needed evidence he had paid for it.

We had you comb through your files, which included copies of his medical bills, his death certificate, proof of your executorship, and his monthly and year-end Social Security statements. Those statements showed Part B premiums were being deducted. You also found his Medicare Part B card. Even if you had not been so organized, you still could have gotten your proof: Any Social Security recipient can get copies of his or her statements through a local Social Security office. Executors can also get copies by showing proof of executorship.

We sent copies of your records to Social Security. Benita A. Dallas of the Atlanta Regional Office says your father's ineligibility was "a computer malfunction or just human error." Within a month, we were notified that your father's Medicare Part B coverage was reinstated for the period in question. Kaiser says the bills will be resubmitted to Medicare. And the collection calls have stopped.