Wrong amount debited

I owe R10 000 on my credit card, the amount owed gets debited from my cheque account. In December the bank tried to deduct an amount of R1600 instead of R300 (i.e. minimum repayment is 3% as per the agreement with the bank). The payment bounced as there was not enough money in the account for the wrong debit, the debit was reversed and a penalty fee was debited. I noted this problem on the standard bank web site, a lady called me back and stated that I was correct and the amount debited was wrong, she however could not assist me and said I needed to phone the credit card division (the first call was on the 28/29th of December 2015). I phoned the credit card division on the 5th of January 2016 (reference crb 2379, 8:45am), I stated my problem to the lady however she insisted that the amount of R1600 was correct even though this is a repayment value of 16%, not 3% as per the agreement I have with the bank, during the call she also noted that my account does not get debited and that I make payments manually every month (this is also untrue). After a long and unfruitful debate I asked her to investigate, this has not and will not happen. Can this get sorted please