not allowing me to close my paid up credit card, claiming i owe more money

i have paid my gold credit card in full, to such an extent that when i enter my mobile banking it shows i have R7 credit over and above the R10 000 limit that i have on my credit card. when i went to my branch on friday to close the account, theyphoned the credit card department which said that i still owe R63. this is pathetic, what for? it doesnt show anything like that when i enter my mobile banking, and they say that becasue i can only pay it at the end of themonth, so this allows them to charge unneccesary fees to my account, in the process *****ing my hard earned money becasue they are greedy. I am not going to pay anyting more than what i had to, and i expect my credit card account to be closed urgenlty, as i dont want it anymore!!!!