I paid my credit card in FULL and requested the bank to close the account

I paid my credit card in FULL and requested the bank to close the account. My credit was R15000 then l paid R15.500,only to find out l have to get the settlement amount from call center of which I did. I was left with R284.86 and l settled the amount. I then called for the closure of Amex.,to my surprise I was told l owe R80. I called the call center again to get clarity, my calls were dropped 4 times by different people WITHOUT help. To make matters worse, l asked for the manager, a lady by the name of Lindy attended my case. She promised that by Tuesday the account will be closed ,she gave me this ref number ***1and she will call me the following day. The week is finished my account is still not closed and none came back to me. The service is one of the worst l ever experienced,stinking and disgusting.