About 4 years ago I went the XXXX XXXX XXXX XXXX for a XXXX issue. A portion of the visit was not covered by my insurance. I paid the bill I was sent to the address I had on file. I sent the final payment of {$37.00} on XX/XX/XXXX. Unbeknownst to me, the XXXX company had changed collection firms and I was supposedly sent a bill with a different address for remittance. I did n't learn any of this until nearly XX/XX/XXXX when I started getting phone calls at all hours of the day and night 7 days a week from XXXX in XXXX, NC. I sent them faxes of my cashed check showing I had paid. They said I had to contact a company in CA ( the XXXX XXXX XXXX XXXX?? ) which I did. They were rude and told me I had obviously paid the wrong people. I paid XXXX XXXX and they cashed the check. I suggested that they should be collecting from XXXX not me. Well ... the calls stopped for awhile but they circle around again for several weeks at a time. In my humble opinion they could have written this off 3 years ago - or better yet corrected their records as I DID pay the bill - and saved a lot more money. I no longer answer the robot calls and I do not answer the " real person '' calls as they do not listen when I provide them proof that I 've paid. It 's extremely annoying. I have moved since this all started and I am not sure I can put my hands on the original documents anymore. BTW - I NEVER received a past due statement except for the XXXX I ignored because I had already paid the bill. I NEVER received any communication from XXXX, the XXXX XXXX XXXX or anyone else until that XXXX phone call in XX/XX/XXXX.