Money for Nothing

My landline stopped working on 31st October. I was actually delighted that having logged the fault, a technician arrived the same day! He couldn't fix it and assured me he would be back the next day. No amount of follow up got any interest from Telkom in fixing the issue so instead I cancelled the service. Do bear in mind that my last invoice was for the service in November but to be clear, I HAD NO SERVICE. Telkom expect me to pay the bill because there is a 30 day cancellation period. How can I pay for a cancellation period when I HAD NO SERVICE. Come on Telkom, wake up. Credit the invoice.