Telkom Billing and contact.

I have had a data contract with Telkom for 7 or 8 years. It is a fixed fee of R199 for a fixed no Gb. I had no billing issues until August. I suddenly had a direct debit for over R600 and have also now received a account for over R700 . I went to the Menlyn branch of Telkom who said that the accounts department would call me. I never received any calls. I went to the Grove branch where a young man by the name of Mpho assisted me in a friendly and helpful manner. He managed to find the fault and promised to get the accounts department to contact me to fixed the error in billing. This time they actually called and the problem was explained to them. The assistant tried to resolve the matter for a while and then said that she needed to check on some information and would get back to me within half an hour to an hour. That was 2 days ago. i tried to escalate the problem but it seem that it is impossible to get the calls phone answered, both at head office, the accounts department or at branch level. It appears that there is no way to contact anyone who can actually resolve the problem.