Horrific accounting from Telkom

I have been a Telkom Fibre customer for over 2 years and 2 months and my monthly invoice has only been correct for 2 months during all that time. It has been a constant battle between their accounts department and their sales department who according to the accounts department have loaded the discount plan on my package incorrectly. I spend at least 30 minutes on a phone call to their accounts department and their sales department every month to get the problem rectified, only for it to be incorrect on my invoice again the following month. I have emailed Telkom's Back Office on numerous occasions with a "read receipt" only to find out that they never even read my emails. According to the sales consultant that I spoke to today, the sales department can no longer rectify packages and discount plans that were uploaded incorrectly, this now needs to be done by the Back Office who never reads their emails or responds to notes that their colleagues put on the system for them to resolve the issue. I am very frustrated and I think I need to take my business elsewhere.