Service Fees payable for NO service rendered!!

I paid the balance of my creditcard in full on 2015/05/25. I have not used this card since. Not only do they charge me almost R200.00 for making the payment (can you believe), they today (2015/07/08) claim that I owe a total of R 762.21!! For what? \Service fees"?? What service? I have not used my card again! And R 762.21 for about a month and a half? That is *******! I will close this account and Nedbank will never see me again!!"""