Internet drops every few minutes. No support.

My devices disconnect within 2-3 minutes of successfully detecting and connecting to my home WiFi. When trying to reconnect, my WiFi is not detectable, Xfinity app shows my modem to be online but tests show it has about 16% speed. I go through trouble shooting and restart the modem. Restarting makes my WiFi detectable again, my devices can connect, and the WiFi test shows the speed at 100%. But then again, 2-3 minutes later, the cycle repeats itself. I have not been able to speak to a live agent and the app chat features has been going in circles. I either want this resolved before I start a really busy rotation, or I need a refund for my subscription as I have not had any consistent connection.