ISP Fibre provider

Webafrica is the worst ISP provider I ever dealt with, I currently have a Fibre package with them that is uncapped and supposedly un-throttled, it was all good in.the beginning but recently the last to months have been a nightmare, Fibre keeps dropping to almost 15% of.my package to going offline 3-4 times a day, and overtime I log a call they only do a reset, I have complained on numerous occasions, I was told they don't sent people out to check lines and routers I must do that out my own pocket, so I did exactly that and turnes out nothing is wrong with the line nor the router, so I asked what's the problem then, I was advised by this independent that they suspect I'm being throttled by my ISP provider, when confronted they deny this, but yet they can't sort out the problem.