Would like to talk to a representative about unstable internet

I have had trouble with my internet connection for a little while now. At first, the connection kept on dropping (sometimes for a few minutes, sometimes for hours). A technician came to my house (and I was charged $100 for the visit) and changed a cable. Since then, instead of dropping the connection becomes unstable regularly through the day. As I was on a Zoom call a few minutes ago, I again got a warning that the connection was unstable. Meanwhile, I tested the internet connection on the Xfinity App. Got a result that the speed to Gateway was 0 instead of the 800 Mbps. All devices were receiving strong WiFi according to the next test. I tried to contact a live representative (with no luck) through the 24/7 assistant. The assistant ran a few checks and stated that everything was fine with the problem being the app.... Tested the internet connection again via the app that stated that the was a problem with the Gateway and it needed to be restarted. I can't just restart the gateway in the middle of calls. This issue is happening everyday and I would really help with troubleshooting it as it is becoming a real issue for my work.