Can't get credit card account closed.

I have a platinum credit card which I would like to cancel and close. I have paid the amount owing in full and I was told via email that I still owed R313.19 interest before the account could be closed. I paid this amount and sent in the account closure form yesterday morning at 8:30. Today I received a test message to say that I owe R100 on this account. I checked my statement and all it says is Fees. Previous statements show a \Fees\" amount of R87. Now suddenly its R100 and this account is supposed to be closed. I have sent emails requesting this to be reversed and the account closed but have had no response. Please reverse the R100 and CLOSE the account."