ADT Durbanville worst service ever.

We closed our account in 2019. This year i get a phone call from Shapiro law firm on behalf of ADT saying I owe them money. In 3 years time i have had no knowledge of any account not been settled at ADT. They have never contacted me before to tel me this. Why do I get a phone call three years later. I have phoned ADT 3 times everytime they put me through to accounts end then just to say there is nobody answerinng at accounts they did send an email and marked it urgent. I am going to have a bad credit score due to ADT 's bad admin.... maybe this review wil urge them to fianlly answer there phones.... worst service and costomer care ever... are they going to clear my name..... probably not I am just another unhappy customer....