Debt Collection and Identity Theft.

Over four years ago, my identity was stolen. Someone opened several accounts with my SSN. I immediatly had these account corrected (i.e. I contacted the original credit companies). I filed a police report and sent signed afidavts. Now in 2006, one account has come back: Fingerhut. This company has since sold the account (after agreeing that it wasn't mine) to Compucredit, Truelogic Financial and now Midland Credit. I've send dispute letters to all four companies, I've sent cease and desist letter, contacted an attorney and requested verification of the debt. NOTHING...instead the bill keeps getting sold to new agencies who continue to call and harass even AFTER I explain the situation. How can you stop them from selling an account?? I'm in the junk debt collector HELL and I can't get out...and it's NOT EVEN my bill!!