Poor/ No service in trying to resolve issue of not being able to recieve calls

I renewed my contract 2 days ago. Since that day I am unable to receive calls. When anyone calls me they simply get "the number you have dialed does not exist" or "the number you dialed is incorrect". As someone who provides a 24/7 service to my clients, this is a HUGE problem. I have tried customer service number "135" and the only option that got me to a operator was saying I want to cancel my contract. When reaching them they gave me call barring numbers to call. This still did not work. Finally after speaking to three different operators I deiced to drive to the MTN Store - Castle Gate Lifestyle Centre. The staff here were extremely unprofessional talking behind the counter for 10min before looking at me and asking if I need help. They logged onto my account and said nothing looks wrong they can't do anything. Upon pressing that I need this resolved, they phoned their own customer service line and handed me the phone. At this point I handed the phone back to them and left, indicting they are wasting my time. At this point the problem has STILL not been resolved and I am at wits end to what to do next. Cancelling my contract seems to be my only option at this point.