MTN anti-competitive

My contract has ended in October and I have been sending emails and sending DM’s to MTN to cancel my contract and do something about my request but MTN simply ignores me. Intact they say they call me but I am with my phone everyday and no calls from MTN. This is anti-competitive behaviour and ********* behaviour by MTN. Because the longer they ignore me the more money I pay for a contract that has ended in October already and that o have cancelled! The ombudsman needs to hear about this.