G36- Slow/intermittent internet connection

I have a new G36 with spectrum as service provider : I recently spoke to spectrum for the reason of slow speeds and continually intermittent connection. I have 1000 mbps and 6 month ago I had spectrum come to my house run a new line inside and out side . Can I get a solution for this I dint find any other way to contact you for service and spectrum blame the issue on my modem . Thank you