Cancelation of a business line

I requested the cancelation of a business line on the 20th of May, to date we are still being billed for this account. I have tried to contact the call centre for the past week, without success. After holding on for half an hour for some bizarre reason the call is diverted to sales who cannot help me and I get put back on hold all over again. I have even sent an email to the escalation department and have not received any response either. What must one do to get any assistance from Telkom???