Wrong judgement

I once had a Jet account and paid it monthly , My installments were up to date and didn't owe them anything. All of a sudden I owe jet and the Shapirro lawyers, I don't even receive calls from their debt collectors because I don't owe them. My credit score is down because of this nonsense. This is not fair, is this how we get treated after being loyal customers??? I want my name to be cleared on this incorrect debt that I am being labeled with.