TRYING TO CANCEL A CONTRACT WITH MTN

I have been trying since the 21st December 2015 to cancel contract that I have with MTN. I told customer care that I no longer live in SA, I was told not a problem a cancellation can be done on email, I just need to give them all the information on email, which I did. I have tried on numerous occasions to contact MTN on their *** number and always get, the number you have dialed does not exist! on the 28th December I was told it has been sent to the Retentions department and they would get back to me with the cancellation. now 2 months later I am still be charged for contract I DO NOT want and every time I contact MTN I am told it is with the Retentions department.. what does one have to do to get a contract cancelled with MTN.. Never in my life have I experienced such bad service!!!!