Bad Service from MTN

I am looking for opinions on what to do about the situation I am in. I took out a contract at MTN last year February. In November last year my phone started giving me problems (not charging), I took my phone to Montague Gardens to the repair centre because the stores in Somerset told me that I have to wait for a certain day in the week when the company collects the devices to take to town. They booked the phone in for repair. I waited 3 weeks for my phone then got it back. Two weeks later, my phone had the same problem and was booked in again. My phone then worked for a while and then starting with the exact problem. We drove once again to town to take it and then the phone was sent to Johannesburg for repairs and I when I got it back for the third time from repairs I recieved a new charger. 2 weeks ago it started giving me the same problem. I am so fed up with this. I get no loan phone while my phone is in for repairs, they dont let me know anything about my phone and they deny giving me a brand new phone. I think this is flippen ridiculous!