Frequent internet drops on wi-fi and ethernet

Three weeks ago I began experiencing 2-minute internet drops every 10 minutes. Devices on the wi-fi would drop, my ethernet-connected PC wouldn't load pages, and pinging the DNS server showed that there were many timeouts. Pinging my modem showed that there were no errors between my computer and the modem, everything perfectly smooth. Despite that, Xfinity tests showed no problems, and my own PC's tests showed only "Low internet quality." I have already done every troubleshooting step, reset everything to default, power-cycled every device many times and checked for hardware faults, but nothing has helped.

The hardest part is that I'm paying for a high tier internet connection and the Xfinity chatbot just takes me in circles telling me nothing is wrong. I get that customer service is a rough job and there are many angry customers at times, but I just need a human being to help me get a refund for all this time wasted trying to fix a service I pay an entire week's worth of groceries for. I got through to a human one time and he tricked me into paying for a new service so that I could replace my modem in case that was the issue. Replacing the modem did nothing and now I have extra bills to pay. There is literally nothing left I can do to solve this problem from my end, I just want someone to actually help, please.