Incorrect Billing

I have reached my last straw in resolving my cell phone account. I've been receiving invoices which do not correspond to the contract amount which I agreed to and accepted. I have a corporate contract with MTN. I downgraded my package from an MTN 350 Top Up to an MTN 200 Top Up. I was paying approximately R416.00 p/m and with the contract downgrade I was expecting to pay R368 p/m as per the application recording. When I queried it with the credit control department, I was told that I have to now pay R449.00 p/m which includes an amount for the phone. This was not agreed upon and accepted when the contract was compiled. After much communication with MTN, I was told that the matter was resolved. This lasted a month!!! My monthly subscription then reverted to R413.00p/m. I have tried to resolve this matter again and again but am failing dismally. It seems MTN takes no interest in resolving the matter.<br> <br> I demand that MTN resolve this issue IMMEDIATELY as this is utterly frustrating and pathetic service or lack of it.