Account payment

I had bad experience with Ackermans I had an account with them I paid it off since I have been unemployed.I got an email from them saying I have made a purchase of a cellphone at Cape Town and replaced my which I didn’t even use my account now I am getting called every day about a payment I have explained myself to a number of people who call me every day they I must make an affidavit which I did and sent to them with ID copy that has my signature they rep**** and sent me a form that I had to fill out which I did but they still calling me about payment