Continuing Intermittent Connectivity Issues

We have been dealing with Comcast's intermittent service for several months.  Level 1 India techs couldn't help.  We finally got a new modem......and the connectivity issues persist.  We finally get a Tech to com out and inspect our system.   He replaces all the connectors and shows a strong signal to the modem.  However, the intermittent service persist.   It is either on or off.  Modem diagnostiscs say everything is fine.  If I call level 1 tech I know what they are going to say.  I'm not sure what my next move is.