Bad customer service

Good day

Let me start off by saying I'm very, very disappointed in MTN. I took out a contract at MTN to be specific MTN Mossel Bay in July. 10 days after receiving the phone, it gave me trouble. I returned it and seeing that it's pass the 7 day exchange. I was told they'll send it in. The warranty was declined, why I do not know, but repairs on the phone was approved. I don't understand. The lady who was dealing with it at MTN is Marshia Maart. The MTN outlet is MTN Mossel Bay Mall. She sent in the phone and 3 weeks after it was returned and nothing done to the phone. It was sent away again and up to today Marshia and MTN Mossel Bay has no feedback for me. I've been paying for the contract, but the phone has been with MTN for more than a month. What am I to do?