Poor service from Telkom Call Centres., and no support from agents

I am continually receiving an invoice for a subscription that was supposed to have been cancelled, as per the Telkom Sales Team, when my subscription was MIGRATED to DSL as enabled by The Sales Team. I have repeatedly logged complaints in this regard, on the Telkom website, but to date, have received no feedback. I have left callback requests for the sales teams to contact me, but nothing has happened. The last call I received was when I was in the process of parking my car, and I requested the agent to call me back as it is a dangerous practise to be sitting in a motor vehicle, whilst talking on the 'phone, especially in my neighbourhood. He did not call back.