Disgusted with African bank!!

My debit order amount was a set amount each month,upon my last debit order(which I thought),a quarter amount was deducted which indicated to me that thiswas the whole outstanding balance,also my statement for that month indicated x amount would be my final deduction,i phone after last deduction to close this credit card,african bank consultant confirms she cancelled and closed credit card.following month I receive a statement for 90 rand which I justify as interest that I have to pay,today 100 rand gets deducted,i phone to confirm that this was the last deduction and to my horror I find there is still a 'small balance with interest I need to pay!!!!!I ask consultant why did you not clear my balance with last deduction as that amount was only a quarter of my normal installment!!response is I just have to pay it as there is a balance,she doesn't know why upon cancelling the consultant confirmed card was now closed and no balance anymore!!African bank are ******* and people should not do business with companies with no integrity!!!!