Intermittent connection/latency issues

I am constantly having intermittent connection/latency issues. I remote into different machines for work and am constantly having latency disconnection issues. On my teams call I am constantly sounding like a robot to everyone else and it is clear my chat is constantly delayed. Comcast wont send anyone out and I have purchased an extra modem, extra router (didn't need to because problem still happens hard wired from pc to modem, tried multiple pcs), and upgraded my plan to the highest available (shouldn't matter for latency). 

Every time I call comcast I get in the loop of "based on the error code from your modem, we need to reset", I call back 10 minutes later and it just tells me the same thing over and over. If I reply to the text asking if I am still having problems it just says "There is an issue connecting you to an agent right now. Please reply back with another READY in a few minutes...". No way to talk to anyone and unable to do my job. 

All of my modem downstream and upstream levels are good (both old, and new). I have ordered 3 couplers and extra splitter and am currently only having the line coming to my house coupled to a wire that goes directly to my modem. I was just getting 8mb down from speed tests for a solid hour when paying for gigabit.

I really need this connection fixed and am going crazy from all of the comcast loops I keep getting stuck in. PLEASE HELP!!!