Cancelled contract still being billed

In December 2014 I cancelled th MTN contract for cell *** and ported the number to vodacom.<br> MTN continued to debit my account for the cancelled contract.<br> Finally on 24 August 2015 I managed to get a call centre agent on the phone to discuss.<br> I was given a reference number and was told the problem would be resolved in 48hours.<br> It is now 12 days later the 5th September 2015 and still nothing.<br> I tried to call MTN this morning and after waiting too long for someone to answer on the phone I gave up.<br> I am hoping that MTN has capable people that check these hellopeter complaints and can resolve.