is your service Business Class or Residential? I have BC and when I have had problems in the past they sent a tech out the same day. also, when you are having problems, log into your modem's diagnostic page and record things like upstream power, downstream power, signal to noise ratio and everything in the log area. it also helps if you have something like PingPlotter running pinging your first comcast hop. now with all this information at hand, call tech support every time your service is down and give them all the information you have collected. keep track of who you talked to, the tracking number and the date and time of the call. if the problem persists, ask to have your problem kicked up to the next level. if all that fails, ask to speak to a supervisor. if that fails, call and ask to speak to a customer retention rep. if you still can't get the problem resolved, it's time to switch providers. all this works MUCH FASTER if you have Business Class Service!
Good luck!
Roy…