Telkom Billing for more than what on contract and dont want to resolve

For the last year Im having issues with my billing with Telkom. When trying to contact them they sent you from sales team to billing which not in communication with each other. The sales team on numerous instances acknowledge that the bill is incorrect and I need to pay a total of R1538 but I keep getting billed for R200 to R300 more. Tickets are logged and closed without any resolution or feedback.