POOR Service!

I have cancelled my contract in March already only to find that they have only cancelled one of the numbers and not the other contact. I tried calling in to the MTN retention department and to my disappointment i have been on hold for an hour to 2 hours only to get cutt off everytime. Their service is extremely poor and the only feedback i got from facebook was sorry they are experiencing high volumes of calls. I think this is bull**** as i have also been trying to email and no response. What do i have to do to get a contract cancelled? I feel as if this department have taken the phone off the hook on purpose. They don even deserve a star to be honest!! Am taking my business to Vodacom.