Fiber Speed Issues

I've been now with Bitco for a few months. I have the 1000Mbps Download package via Vumatel. After installation I received an average speed of 900 Mbps with which I was very pleased. Sadly with time the Speed has now dropped to an average 400Mbps. I've contacted Bitco support and even Vumatel. Both just tells you that the problem is with the other one. Then I need to do "hundreds" of speedtest for them... Looks like they can't do the speed tests on their side... Oh and they love closing tickets without resolving it.... Looks like I'm going to have to cancel the service and try yet another ISP...