Incorrectly billed ( ******)

Telkom is just something. My DSL line was suspended due to an amount I was owing October on the 15th. Bare in mind that it's a month to month deal, but strange I was billed for November which I didn't even use the service for. I called them 2 weeks back to cancel the DSL and line rental with them. I was told to pay all the amount I was owing even the one I was incorrectly billed for a month that I didn't even use their services. I paid the full amount including the one that they billed me. I called them again last week to cancel my services they said I can go to the website to do so. Did that to their website and cancel but nothing was done all I got was a reference number. No1 called me to finalise it, I call them again yesterday to help me with the cancellation and the lady I spoke to Noxolo from Telkom call centre in Cape Town, said the cancellation should have been processed because on their side it shows that I'm not owing anything. Then now I receive an invoice saying I must pay another R1000 which I don't even know what is it for. It says it's for December service while my package is only R799 and my line was up to date after paying and I haven't been using their services since October when my line got suspended.