Internet dropping, techs not fixing

I've had technicians out 4 times. Sometimes Internet is fine for 8 hours, it rained today and was out for 4 hours. Sometimes it cuts out for 1 minute sometimes 10 sometimes an hour.

Disconnected each device in turn and waited, none were the issue. 2 new routers later confirms that's not it. No splitters in the coax or visible kinks. 

I've explained the situation to a few different Xfinity people now, and eventually they end up sending another technician out, the internet decides to work fine for a minute, and they leave. Now they're saying I'm going to get charged if they don't find anything wrong? Frustrating.