Spam

I have tried on numerous occasions to cancel marketing from MTN..Went into store was told to do the *135* or whatever it is does not work!! I receive a message thanking me for unsubscribing, and them get bombarded with messages again ..MTN I need you to stop sending me and to unsubscribe me from all the spam that you are sending with immediate effect. And do not say there is an opt out option because that does not work either..