Vodacom fibre slow and unstable

I have a a 4mb uncapped fibre line with Vodacom and the speed on it is quite sad. My ADSL line which was also a 4mb line was much faster and much more stable not to mention half the price. Vodacom Technicians keep saying unplug the router and plug it back in again which tends to work for one day and then it’s back to being a sad excuse for fibre. I think it’s about time I find a new service provider