They sent me a $500 bill for an account I knew I h...

They sent me a $500 bill for an account I knew I had a 0 balance on because I had just paid the most current bill which was $9. As soon as I asked for a full written accounting of the debt they came back with "oh this account is now showing a balance of $266". When I replied to tell them again that I just paid the most recent statement of $9.43 and can prove I don't and never had a balance with this client and told them my attorney would be the next to contact them, they suddenly emailed me back and said the account shows a 0 balance and was being sent back to the client. I'm assuming if I would have just blindly paid that first $500 bill I wouldn't have gotten that money back. Be careful with the debt collectors everyone.