NO SERVICE WHEN CANCELLING A DATA CONTRACT

we have a data contract with MTN, and for the past 25 days (since 1 August) we have been trying to cancel this contact. So it begins with phoning ********** , you go through the whole automated process until you finally get through to a call center person, you tell them you want to cancel the contract, give the number etc and they put you through to the Cancellation department, the you hold and hold and hold.... 10 mins, 15 mins, 20 mins, until we eventually end the call because NO ONE apparently works is the Cancellation department at MTN!!!!!! NO ONE bothers to answer the calls to assist us in cancelling this contract so I've decided that i will simply stop paying them... as easy as that. We have tried going the MTN Shop for assistance, but they always give the same old excuse, "they cannot assist, you must phone the number to cancel"!! The service is really horrible!!!!!!!!!!!