Telkom: Bills you, then ignores you

I have had a Telkom account that I used for my ADSL connection for 3 years. MWeb handled the ADSL conversion and the internet provision. In July I requested that both parties cancel this line. MWeb did (with the required months notice). In early September I received a reference number from MWeb that they had received from Telkom confirming that MWeb, my ISP, has returned the line. My request to cancel the line was logged on Telkom's website and I made numerous email and phone queries to request cancellation. In spite of this Telkom has ignored their own reference number and my request to cancel the line and continues to bill me. I have never experienced such a level of apathy from a company for their customers.