MTN not processing cancellation of contract

I contacted MTN on the 13th or 14th of April to cancel the two contracts I have with them, as I have moved to a new service provider. I was told that the cancellation was accepted and that I would receive a confirmation soon that it had been canceled. Since then I have yet to receive confirmation on the cancellation, in fact now when I phone MTN to follow up on this I am told that there is some problem with the processing of the cancellation and that the matter has been escalated, who to or for what I do not know and nobody seems to be able to give me a time frame of when this will be resolved. This morning I was told yet again that it had been "escalated"... In the meantime I keep receiving calls from MTN, telling me that my contract is due for an upgrade!

It is now 4 weeks after I originally requested the cancellation of my contract and I need someone to sort this out before I have to pay for another month of MTN that I do not want. I am tired of hearing that it has been "escalated"!