Billed fully for incomplete FTTH installation

Vodacom has been billing me for a FTTH (fibre) service that was installed in December 2017. Upon initial installation of the router, the technician confirmed that the line that is supposed to operate at 100Mbps, was only running at 10Mbps. I immediately reported this to the sales consultant, who nevertheless ignored my complaint and marked the SO as completed. Subsequently several calls have been logged to try and resolve this issue: SR180 ********** 32, SR180 ********** 88, SR180 ********** 97. The first two calls have both been closed without any final feedback to me, and it seems the third one is remaining open indefinitely.

In the mean-time Vodacom sent me a bill for more than R3000 for usage of a service that has never been confirmed as successfully installed. The first time I could test a line speed of close to the 100Mbps service was some time on February. I keep phoning the Vodacom Fibre Helpdesk, but no one can assist me. I just keep getting placed on hold, while no receiving no updates via email.

The last SR was logged telephonically as a dispute of the bill, but the person who assisted me wrongfully logged it as "Vodacom Fibre , Flapping / packet loss". I find it infuriating how Vodacom simply ignores any request to dispute billing that is based on their inability to deliver a service as advertised.