Incredibly Slow internet for 4 months now

This is the most frustrated I have ever been with a company. I pay for 1GB internet and have had absolutely horrible service for 4 months now. I’ve been getting either no internet at all or sometimes 10-50mbps. On a rare occasion I might get 400mbps but that only lasts for a couple minutes. I’ve replaced my modem 3 times, replaced coax lines and Ethernet cables as well as had 2 techs come out and say it’s a node issue but here we are with nothing done to fix the issue. I just want normal internet service like everyone else. I would’ve canceled long ago if there was literally any other option for ISP. How do I get my internet fixed?