Telkom - good for nothing fiber optic lines

I am beyond irate and frustrated with Telkom. I have been continuously paying for a service that I am not receiving. I have recently upgraded my home DSL 10mb line to a 4mb fiber optic line, which according to the idiots at Telkom is actually a 5mb line. However, I am yet to receive more than 1mb of speed.

I have reported this time and again and yet nothing is being done. I refuse to pay a cent further if my line speeds do not increase and wish to cancel this line and subscription with immediate effect. As per NCA, I cannot pay for a service that I am not fully receiving. The service and response from Telkom is pathetic as little to no help has been given to us.