Wrongly billed and handed over to debt collectors

I had a home telephone line, most of the time I was reporting it to telkom because the line was not working when the weather was raining or moistly. All these times they billed me for the full month. I then went to the branch in Cape Town CBD, which I received the poorest service ever. I asked them to disconnect my line as the phone was not working in most of the month. <br> I then received a call from the customer care confirming my cancellation, the lady then advised me to hold on, on the payment and wait for the Aug statement as they would have updated the statement for the dates when the phone wasn't working. <br> Now in September I received a call from NICS who are a debt collector that Telkom has handed me over to them. This is without any communication with me nor sorting out my statements to reflect the times where the phone was not working.<br> According to the statement that i received from NICS, they billed me for July & August even though the line was not working after the 1st week of August.<br> I need this resolved as I am not will to pay for the line that wasn't working or I will be taking this further.