Unable to rectify an outstanding amount

Since last year May I have been unable to rectify an “outstanding” account for my Telkom ADSL Line. I went instore to cancel my line as I was selling my house at the time. They informed me I have to send in a cancellation document and was not able to do it instore. I managed to get hold of this document and sent it off on the 4th of May 2016. There was no responce. I then sent through the document again. A couple of weeks later I was informed it was cancelled. I never had anymore responce from Telkom after that. The beginning of this year I was messaged stating that I owe Telkom a sum of money. I then called and stated that I have cancelled the line and that this was not possiable. Since then I have been trying to rectify this “outstanding” amount. Last week I called Telkom again. I re-sent all the documents and was told they are able to see the fault and logged it - also I was informed it would be rectified. Today I received a call, the lady that spoke to me was rude and totally unprofessional. She stated that I owed the same amount that I have been trying to dispute. I asked her to please explain why and how I owe this as I am unsure. She responded that she has already explained and then asked must she really explain again, to which I rep**** yes as I don’t understand. Then she hung up the phone. I don’t know why I am owing this money. I am being bombarded with lawyers and I have been listed. No one can explain to me why I ow over R1200, when my monthly installment was only R360 about. I was a good payer and now I am listed on ITC!!! Please could someone provide clarity!