Vodacom Fibre still failing in Hartbee****rt - this time throttling connectivity speed

I have a Vodacom Fibre installation since 20th March 2019 - it has been failing every month. This time the connectivity speed is less that 10% of the contracted SLA. The Vodacom Call Centre is no joy either - Cassandra was unable to provide support, and her manager, Surika tried to convince me about static IP-devices and too many devices connecting to the same router slowing down my download speed (although, for the past year I have had adequate speed with the same number of devices connected). It is,however, strange that my connection speed picked up to the SLA-levels whilst we were talking - this leaves me with no explanation other than Vodacom throttling their service to selected consumers in order to compensate for inadequate infrastructure capability.