Unresolved matter on unauthorized billing from Telkom

On the 28 September, I had requested for my Telkom contract to be cancelled and I received a confirmation from Telkom indicating that my contract has been ceased and that it has been sent to the billing department to waive penalties. On the 06 October 2017, I received a bill from Telkom penalizing me for cancelling the contract. I then sent the invoice to the lady who indicated that I will not be billed for the cancellation and asked for assistance. She then assurance me that she will follow up with the billing department in this regard as they were instructed not to charge me for the cancellation. I have not received any feedback from Telkom even after following up twice. I do not want my name to be blacklisted due to this ******** bill. Can someone please assist me.