Telkom's incorrect invoicing

Since switching to a Vumatel fibre line and using Telkom as a service provider in May 2018 I have been grossly overcharged by Telkom. Despite numerous telephonic conversations with Telkom. My bill is STILL incorrect. I had even resorted to cancelling all other subscriptions with Telkom and just leaving Telkom as my service provider. Guess what....My bill is still incorrect. It looks like my only other option is to cancel that as well and move to Mweb. I would rather settle my remaining 4 months of the contract upfront and move to a more reliable service and pay more per month than to keep wasting my time fighting.