MTN - worst service provider

I am unable to make calls from my MTN number since December 2014. I reported this problem more than 8 times and to this day MTN gave me no reasons or answers. One of the proposed solutions was a SIM swop which I did and that also did not work. Most of the 808 operators just tell me to take out my SIM and switch phone on again after couple of minutes - and then I will be able to make calls again. But this obviously still did not work. At one of the MTN shops one of the staff members also reported the problem to MTN head office (3 times) and still no solution or any feedback from MTN. No one is giving me answers or getting back to me on the numerous complaints I lodged. MTN please give me solutions and FEEDBACK!!!!! You are by far the worst service provider ever and I will most definitely not renew any MTN contracts again. I am fed up!! I pay mu contracts on time each month but I am unable to use the phone for its intended purpose. This is not the first mayor service problem I had with MTN>