What happens at the Telkom billing department? Is anyone held accountable for requests? Pathetic

I canceled my Telkom ADSL subscription in 22 May 2018. After months of battling to have this service canceled as I was still being billed every month, it was officially cancelled in September after threatening to lodge a complaint with ICASA. I now find myself in a position where the service has been cancelled and my billing has not yet been backdated I find the process extremely frustrating and the turnaround times poor without any delivery/. I've logged several billing requests of which Telkom now needs to Credit me for more than R2000 , I've been billed yet again how do I constantly pay if the billing has not been corrected, what is the true reflection of my invoice. Telkom has great offers however in terms of billing & customer service they suck.