Harrassment by African bank after paying up my credit card

<p>I called African Bank in April 2017 and enquired on how much is outstanding on my credit card so that I can pay it off and close it. They told me the balance, which i paid on 13 April 2017, thereafter African Bank sent me a paid up letter on 19 April 2017.... However, on 15 May 2017, they deducted the normal credit instalment again, which i reversed and stopped because my account is paid up, I called African Bank they said they opening a query and will revert back to me within 7 days, still waiting. Today, 06 June 2017, am still receiving messages from African Bank saying my credit card is in arrears, i must make a payment. I called the collections department, they telling me that my account is not closed, am still owing because i reversed the May payment, ***, I paid up my account in April already, and they confirmed that by sending me a paid up letter, i had every right to reverse the May debit order. African bank are just ******</p>