Poor poor service, zero customer care

Have had an account with MTN for too long now! Finally my contract is up and I do not want to continue with my contract. I had a million calls for upgrading and when I said no I was told I need to then give notice to cancel which I did, and I did this a month before my contract was to end. Come the following month and I am billed yet again but I am charged more than the usual contract amount since now I apparently move to month to month. I call to tell them I have the email with all the back and forth proof of my cancellation discussion with customer care only to be told well we don't see it our side. Whose fault is that?? And I still must fit the bill??? Makes absolutely no sense