This company collects very old debt records and attempts to collect whether you have paid the debt in the past or not. They are banking on you not having proof of payment since the debts are alwyas at least 5 years old.
I have emialed the reciept for a debt from 2009 which I paid in full but they refuse to accept it as proof and continue to harass me.
They are counting on paying the debt costing less than hiring a lawyer.
If you are recieving similar treatment by these scammers, submit a report here:
http://ehome.uspis.gov/fcsexternal/default.aspx