Impossible to cancel account

I've been trying for five months now to cancel my old apartment's adsl account with Telkom. After multiple phone calls, emails and visits to the store, the most i have ever got is that it will be escalated and the subsequent charges will be reversed. I have emailed agents' personal email accounts with the promise that they will see to the matter or refer it to a higher power. Today i got a call from an angry debt collector telling me to pay an outstanding. Does anyone that I have access to speak to at Telkom actually have the power to cancel this account.