Continually billed for a line that has never worked and that was cancelled

I app**** and had a Telkom line with internet installed during a promotion they had run in January. The internet worked for one night only and after 30 days of trying to get it sorted I finally cancelled the line. Before cancelling the line Telkom also charged me for the equipment (WIFI Router) that was supposed to be free as part of the package. Furthermore they have billed me for over usage and continue to be billing me even after I have received notifications that my request to cancel my services have been resolved. The service on 10210 is pathetic and I have send more than 20 emails trying to get assistance, all of which have failed. I am still paying for it and everytime I reverse a payment with my bank, Telkom just double debits me the following month