internet buffering and freezing

We are having CONSTANT issues with buffering and freezing. On Zoom, watching streaming channels. I was just told that my discord is letting only snippets through and no one can understand what I am saying. My work requires I be on Zoom most of the day, and having no one catch what I'm saying is a PROBLEM. We just replaced our gateway, I checked the connections in the basement, and they are all tight.

There is NO customer service here, No human, Comcast's bots are less than useless. How do I get a tech out to see what is going on with my service??