I think its horrible how all of us seem to have one of these stories to tell. I've dealt with it a few times as different family members have died. But, they keep popping up every couple of years as one collections agency buys junk debt from another, and I have to go through the entire process again. I now keep photocopied documents that I just send in. Only stops it until the next time.
They true stupidity I dealt with was having one of my own cable company account turned over for collections. I moved from Florida, and gave them my new NY address to send the final bill. They sent it, and I paid it. The next month, I received a bill for $0.00. Then, the month after that, a late notice asking me to pay $0.00 or they would shut off my service. I ignored that one also. Got another one threatening to turn my $0.00 balance over to a collection agency. I called them laughing. The CSR agreed it was a mistake and said she would take care of it. Six months later, I got a call from a collection agency demanding payment (apparently cable company stupidity is contagious)!!! No more laughing matter, because they had tacked on fees of almost $500.00!!! I thought that was a bit excessive. Went back to original cable company and explained the situation. The rep told me I should have paid my bill when I had the chance. I told him to look at the balance on the account. His response was "Oh." In a moment of frustration, I asked if I sent in a payment would that clear up this mess? He said of course. I mailed a check for $0.00 to the cable company with a letter. They cashed my check and sent me a receipt for payment along with a letter of apology. Luckily, enough time has passed since this incident that I can laugh about it now, but it really wasn't funny at the time.