Cannot Cancel Contract

My 24 month contract has come to the end of its term.in June 2015. I visited the \MTN Shop"in Clearwater Mall and filled a form given notice that I do not want to renew my contract . I was given a ref number and nothing has happened except I constantly get sms messages telling me of new offers and then one to say roaming has been added to my account.. I already have roaming so no idea where this has come from. I want to cancel and port to another network. I have been with MTN since 1994 and time to move on. Service is appalling. Whether there is a strike or not its not my problem action is now required but the person who normally responds to HelloPeter is also on strike so there will probably be no response to this complaint as nobody cares. I'm at the stage to stop the debit order and then maybe I'll get action cause the accounts dept. won't be on strike. """