Contract cancellation

I'm so fed up with Telkom one won't get any assistance from that company you go to their stores they tell you to write an email then what's the point of having their stores open if one won't get any assistance,you write an email you don't get any communication from them. My contract has ended months ago and I sent them an email telling them to cancel the contract but they are still debiting from my account what kind of **** is this?I'm sick and tired with this company how do we deal with such companies?because by the look of things I'm not the only one with this problem its so frustrating because I can't get through their call centre after numerous attempts of calling them please guys this company is abusing it's customers and they know that by not paying them they'll blacklist you so that is why they are giving us this kind of treatment...something needs to be done...I curse the day I took that contract with Telkom had I known that it was a highway to HELL I wouldn't have binded myself with that contract...I'm sick and tired!!!