Unable to settle my credit card. Poor service

I had a credit card with Standard Bank and unfortunately it is virtually impossible to settle it. I requested for a settlement quotation and I transferred the funds into the credit card. I specifically asked for the credit card to be closed and cancelled. I then requested for a confirmation letter. I haven't received this as yet but I have only received an informal email confirming that my account is closed. I have been receiving email statements of my credit card and my outstanding balance keeps increasing by R25.00. I queried this and received an email stating that the balance statement was send by mistake and that it wont happen again. This month I received another balance statement and now my outstanding balance is R50.00. I refuse to spend any more money on this credit card. I am not sure what to do so that I can get my credit card account cancelled.