Lien Enforcement Inc Debt Collection Complaint

Lien Enforcement Inc Debt collection department,

I do not know Cont'd attempts collect debt not owed Debt is not mine California

I had a car that I had previously sold that was towed by - - -. I spoke with the company and they informed me that since I had filed out the " Release of Liability '' that the car was no longer mine and that I would not be charged and to ignore the bill that was sent in the mail. I have now received a letter from " Lien Enforcement , Inc that I now owe them money? I have the letter from the DMV showing the release of liability was filled out and processed before the car was towed. I am going to attach this paperwork if the app allows me.