MTN admitted error on statement but won't fix it

On 7 October I received an incorrect statement from MTN. The statement erroneously did not reflect a payment of over R2,000 made on 1 October. I called the call centre and the operator admitted that the error was MTN's. I emailed a follow up. No one bothered to respond to my email. No one bothered to fix the error. This month I received ANOTHER incorrect statement from MTN which STILL did not reflect the payment made on 1 October. I called the call centre and another operator admitted that the error was MTN's. I emailed a follow up. To date STILL no one has bothered to respond to my email. No one has bothered to fix the error. It has now been more than 5 weeks. At first I thought it was incompetence, but now I feel it is a refusal to fix your own error. If you cut me off because I reach the \limit"because you are incapable of running your billing properly"