Absolute worst service I have ever seen

I am trying to cancel my mtn contract but this seems practically impossible. I have been in to the store where I took out the contract where they assured me the contract is cancelled but still the debit order is going off from my account. I have found about 10 times and all that happens is I get transferred from when person to the next(After holding for about 20 minutes) and then the line just goes dead. I have send customer services several emails but also have not had a single rply from them.