It can actually be pretty tricky to identify the insurance company and let them know.
In reviewing accounts for my mother's estate, I discovered that my poor mom had been leaking $4.00 a month from her checking account as an automatic debit, paid to something identified as only a 1-800 number. On calling the number, the voice at the other end announced they were "----- ----- Gold Account Services." It took a little bit of back and forth, but the charge was identified eventually as a policy payment for accidental death and dismemberment insurance on my dad, who had passed away 12 years before.
The customer service representative directed me to mail a certified death certificate to a specific address. The certified death certificate and a cover letter including account information and a summary of the conversation described above was sent by certified mail, return receipt requested. I got back a letter acknowledging receipt. They also indicated that because the policy was established with a third party that they could not cancel it, and that I should call the original 1-800 number to terminate the "Supplemental Insurance."
They took another $4.00 out of the account. Yeah, shocking...
The bank and insurance company tried to blow it off, blaming each other. The bank put a 'stop payment' on the debit, but it mysteriously didn't work. (The insurance unit is part of the bank, but they don't want to admit it. Their stops won't block internal transfers.) Soooo...
I filed a complaint against the bank and insurer via the Office of the Comptroller of the Currency, including copies of the correspondence, call logs, and related information. Copies were sent to the bank CEO (to get into the special complaint handling system often tied to the CEO office), and to the Executive VP for Consumer Products, just for fun.
The goal wasn't to recover anything. The goal was just to cost the bank/insurer more in expenses dealing with OCC than they took from Mom over the last 12 years. Surprisingly, they did eventually pay back 12 years of premiums for insuring a dead person.