MTN *****ING OR NOT *****ING???

I was with MTN for a long time, some times I had problems but Nashua Mobile in Vredendal normally sorted it out. Nashua went to Vodacom and is a Vodacom retailer now. But then we all moved to the MTN in town... My phone is my office and therefor I use it alot... Every month end my limit was reached, I never had a limit when I was with Nashua... Then in May I asked for a port to Vodacom because life was a struggle with MTN at that time. Now six months later MTN is still taking a debit order from my bank account and I have clear evidence(my statements) showing that. I called the bank and they can't cancel it, MTN must stop it. I want to send MTN a bill now with interest... I called our local MTN store, I am still waiting a response. It is a lot of money and I want my money back in my account ASAP...