Complaining about the service at African Bank

Hi I was owing Africa Bank and 2016 my account was prescribed... Last year I went to the bank to ask for a letter to clear my name since I was in bad debt... When I got to the bank I was given an account number to pay the money which I owed the bank... And was give reference as my account... This year I went back to the bank to ask for the letter since I have paid them... I was told by the consultant and the legal that I can not receive the letter hance I payed a closed account... They need to pay me back the money and have a zero balance before they can issue me the letter... It's been three weeks now waiting... I have received an sms which says I can not be refunded because I have no balance... Please help... I have been up n down and Iam not getting any assistance moving forward.