Fully paid Account

I would like to lay a complain regarding harrassment. On Air is calling my 69 year old mother over an account that has been paid off for almost a year now. I personally called them to enquire on the outstanding balance and paid it off but after a few months they started debiting her account. Fortunately she changed her account number but now she's has been handed over for a fully paid off debt. Please retrieve the calls since they are recorded and tell me if she owes you. You are stressing my old mother and stop calling old people to sell them these ridiculously expensive offers.

I know this because I dealt with them before, they started debiting my account years later after I had paid them off.