Telkom Incompetence and Threats

My husband and I have renovated our home and have not had a working Telkom/internet line and connection since May 2014 (Acc no: ***). However, we made our monthly payments as per usual for line rental but decided that we should probably cancel the services which we did on 19 January 2015 - cancellation to be effected on 31 January 2015 under reference number A***0. Despite logging our cancellation, we kept receiving accounts for payment and upon numerous follow ups with the Telkom Westgate office (Patience), we were advised not to pay as billing will be reversed to date of cancellation. We have now been handed over for collection, received a letter of demand and despite responding to same with our reference number we are still being threatened with legal action and listing on credit bureaus. Telkom is refusing to assist, what should be done??? Telkom has not heard the last of this and will from here on out be liable for any legal costs incurred for their incompetence and maladministration.