Paying for full service but only getting half. With no help to fix

Hi have been a long time client of them and have moved up to there 850/850 package on evotell fiber. It has been a great time and it worked. But now since the 5th of may. I logged a ticket with speed issues. I cant even get half of what i am supposed to get. But i have to pay full subscription. Every time i have to find out what is going on. And just get told the ticket is still open and has been escalated. But same old story every time. I have been asking. I got hopd of evotell as they were the guys blamed for the issue. Evotell swapped out my ont, changed my port on the olt. Tested signal strength with a power meter. And according to them they did everything in their power . And my isp needs to investigate further. But guess what i am still paying for a service that i am getting half of.