Dynamic Recovery Solutions Letter stating I owed money to Sprint wireless, Claiming I must have co-signed for someone in another state. greenville, South Carolina

Sent me a letter stating I owed Sprint 1,502.97. Service was from 2002-2003. Nothing was ever paid on the account as I was told. It was opened in a state I did not live in at that time, which I explained. I was told I must have co-signed for someone. Okay if I co-signed you would still have to be in the store so they could verify who you are with proper ID. I called Sprint prior to speaking with them and confirmed I have no outstanding balance as my service ended in June 2012 and final balance was paid in July. I have never recieved any prior bills, statements or anything related to this and I told them this as well and that Sprint confirmed I owe them nothing. As of my last credit report within the last 6 months this item is not on there. I had to put a letter in the mail demanding they cease and desist from any further contact.