I've had it with MTN

The worst experience ever that I had with MTN since having my contract with them for over 6 years. Been ****med by ********** doing telephonic transfers/purchases, showing the numbers it is being transferred to, leaving me with a debit order of R1500 and yet the call center and instore assistance cannot activate my Sim card, that I had since January. I cannot use the minutes but paying for it. So what do I do now since I am left with debit orders every month.