service getting cut and refund

This is the third month MTN cuts my services even though I'm in credit with them. I dealt with a man named Yaseen Ford, emailed him constantly asking him when the refund will be available, no response was given at all.I emailed customer care as well and their complaints department. This morning I received yet another SMS stating that I need to pay R1500 or they will cut my service but all my payments are debit ordered and I am up to date. If they cut my service one more time and not refund me the amounts I paid extra,I will move service providers immediately,The call centre says one thing and nothing happens. I need urgent assistance!