I have had fluctuating internet service for a long time. Every time I call they tell me everything is OK. They give me an appointment for a technician to stop by but nobody ever shows up.
Then I call again and they give me a new appointment and again nobody shows up. Funny thing is I work for the government that regulates cable/communications companies. Good thing is there are more new companies coming to my neighborhood and I can't wait to switch. I already cancelled all my TV service because the service fluctuates and cancelled their phone service because it did work, using OOMA now. HDTV works great with a good antenna and other things I watch on Netflix.
If only Netflix wouldn't keep stopping and trying to buffer with that terrible, fluctuating COMCAST internet service I have. I guess calling them again to come over wont do anything. It's way overpriced in the first place and they keep going up in price. You get a combo of TV, Phone, Internet in any European country for about $30/month and in Asia for half that.
The first time I had comcast I had a similar issue. Crappy TV quality, internet going out all the time. They sent a tech out once and he said he couldn't find anything wrong. About a week later I called ATT and DirecTV and got their services. While pulling up the old cable from my yard I found the problem. The sheething on the cable has been nic'ed when it was being burried and water had gotten in and almost compltly rusted through the copper wire. It was so weak that I easily pulled it apart. I had asked if that guy had checked the outside line when he was there and he said yes. But apparently he lied.