MTN messed up my connection and cannot fix it.

I ported my number to MTN in December 2014. I requested in writing to be put on MyMTN 350 contract, however, discovered that I was put on MyMTN 100 contract. After a month and a half MTN tried to put me on the correct contract. The I was totally disconnected from the network. Since then I am spending hours every day on the phone with MTN Glenfair, the Area Manager and the Call Centre. They simply do not get it right. MTN Glenfair tells me they are very disappointed with MTN, but this does not help me. I am now without my phone for more than a week. I asked for the number of a senior person to talk to. I was given the number of Samantha who is apparently the manager of Customer Services. I called her, but the moment she heard my name, she put down the phone and did not answer again. It is a business contract and I need to be available on my phone for business reasons 24 hours a day, 7 days a week. The more I tell MTN this, the less progress I see. How is this possible? I pay for a service, but there is none. I asked how I can end my contract and port my number to a service provider who can provide service. They cannot even help with this. What do I do????