Cancel contract

I have been calling MTN to cancel my contract and I am not getting any assistance. I will appreciate it if I can get someone to call me and cancel my contracts. Going forward if I do not get assistance in canceling I will reverse my debit order ever month. My contact has ended, I will not be liable for any payments going forward as I am not getting assistance from your call center. I called again this morning and sent an email to cancel. Very poor service