Paid up letter

I am very disappointed and angry because of the extreme low level of services from the Tanacity group. I had a clothing account with them but later on I decided to settle the amount via debt consolidations. The account is now paid up but they are refusing to send me the paid up letter in the name of "you failed to answer security questions" because I told them I cannot remember which store I last used my card at. Now they saying I should send my 3 months bank statement and a copy of my ID, why I don't know since I was paying them manually it was not a debit order. Why do they need my 3 months bank statement. The name of the last person I was talking to is Anele, he refused to give me a reference for the call and said he is the only Anele there. He also said that I can go ahead and report him after I told him that I was going to report them. What a poor level of service I received!