Continuous problems with contract cancellation and no response from MTN

I have been trying to cancel my contract for two months now and I have had no response from MTN's retentions department. This morning they charged me R1299.00 for services I no longer use. I followed their instructions to cancel my contract and, after doing EXACTLY what they said, surely they should have cancelled my contract! What's more, is that on the paper they gave me when I started the contract it states that the contract will end on 26/12/2020!!! I have immigrated since then and I am still having problems with this. I have contacted them on Facebook, e-mail, in-store and through calling their call centre. I now have my South Africa representative phoning them as well with no success. This is utterly ridiculous. I would NOT recommend opening a contract with MTN. If I do not receive a reply soon I will be opening a ***** case against them.