Shocking deterioration in service

I have a fibre connection with Supersonic as my service provider. I've been experiencing intermittent service for days. Usually the service deteriorates sharply in the evening with spikes in latency and very slow speeds. It has now progressed to the same during the day. I logged a call yesterday and was given a reference number after insisting on one. The "technician" was clueless. There has been no feedback. I called earlier, a technician kept me on the line for a long while and then just cut the call. I am currently trying to get through again. Besides my current connectivity issues, their customer service is really quite shocking.