Why must I pay for Telkom's mistake????

I just received a bill from Telkom stating that I must pay R4,376.40 (Invoice nr: 507B***W), apparently I forfeited the contract.<br> I did not forfeit anything, Telkom could not provide me with the service they were suppose to provide.<br> Telkom, please rectify my bill, I will only pay my normal monthly fee( R668.00).<br> I will not pay for your *****-up, because you<br> broke the contract. I can not believe the non-existent service from one of the largest companies in South Africa.<br> I't is totally unacceptable. Sort out my bill right now. <br> <br>