Abused by telkom

This company is the pits, I had a contract with them which expired and when I went into the store to cancel I was informed that I was to do the process online, which I did and to my horror the cancellation was never processed and my bill accumulated as a result, I finally paid and started the whole process again of cancelling and it was stated as cancelled, but now I see on my credit record that I have one number still active even though on my online profile it is indicated as cancelled and again the bill is accumulating and when I called they tell me it is still active, I swear this organisation is reaping us off and it is getting away with it, now I'm stuck with a bill that belongs to a service that had been cancelled,what the hell am I supposed to do with this now