MTN ripping people off

Our contract with MTN expired on 10 June 2015. We went to the store on the 8th of June to cancel and was advised to contact them after the 10th to cancel the contract. On the 15th we called the call center to arrange for this to be done. They advised us to pay R 476 then the contract will be cancelled which we duly did. We went back to the store on the 4th of July to see why it is not cancelled only to be told that there is now a amount of R 298 that has to be paid. I asked numerous times for a reason why we must pay a additional R 298 but no-one bothered giving us a reason or a invoice for that matter. A Mabandla Thusi gave me some sarcastic response that we have to pay it as we did not cancel the contract before the invoice date which is bull as we spoke to the call center on the 15th of June already. I told him these facts and to date no-one has bothered to come back to me. I will not pay the R 298 on this account and the contract will be cancelled as it expired on the 10th Of June already. The number in question is ***. Hows about MTN actually gives good customer service for a change. This is the reason our other two contracts is not with MTN.