Bad Service from MTN

I am very disappointed with the service from MTN. They have the most useless accounting department ever. I recently requested on various occasions to cancel my contract after my 2 years was up and they did not. They just carried on debiting my bank account until I placed a stop order. They then handed me over to VeriCredit. Now I apparently owe them when its not even my fault. I have all the emails that I have sent to them asking them to cancel my contract but no one assisted. I even called their call center and held on for 35 minutes and no took my call. Please can someone assist me cause I am afraid I will get black listed. I will never ever take out another contract with them and I suggest no one else should cause you might be caught in my situation at some point.