Mtn *****ing my money

I have a contract table with MTN for a Samsung tablet. This contact expired last year but mtn has still been billing me for this contract. I have been paying the full fee for the device as well that has passed the 24 months period. I spoke to an agent 2 months ago who told me she will log the refund query and someone will get back to me - no one has called me since and I am still being billed. I have 3 contracts with you and your service sucks with this rogueish behaviour, I also sent this to Kim Basson on Friday but she has ignored my email and not contacted me - I want my money back !!!!