Close my account!!!!

I want to close my account with immediate affect and pay it off monthly. you don't send me my bill for the last month and so I did not know what to pay and I waited but still nothing and ended up paid R200 just to keep my account going and then you phone me and say that I paid late and the payment I made does not count for august because it was late???? what bull is that???? now you added interest to my account when it was your fault?? fix the error on your side, and close my account and lets settle on a monthly payment to get the account paid off, I do not wish to remain your customer anymore.