MY MTN CELL REFUSES TO MAKE OUTGOING AND RECEIVING CALLS.

My MTN cell refuses to make outgoing calls and receive calls, all I get is a call ended error when i try, I can not even call the call center on my cell. All i get is my internet only thing working. (I get a Connection problem or invalid MMI code when i do a Balance check.) When I have called the call center on a different cell, they say they reset something and lot of other excuses and instructions that don't work. They said they have escalate it to head office. My phone is still not working. This problem has been happening for 2 weeks already. This is really frustrating because I'm still paying my contract with MTN and not getting the service Im paying for. Please Help me or ill have to change to a different network.