You can't just chalk it up to the modem. That's only the case less than half of the time, dude. If you want to get a new modem, that's your choice. Get a SurfBoard (SB3100 or SB4100. DON'T get the SB2100).
Also, when you refer to their "crummy support line" make sure you're not talking to the Tier1 folks. Ask for Tier2 outright and insist upon it. Have you actually DONE any trouble shooting of your own? Like unplugging the power to the cable modem for a full 3 - 5 minutes?
When you lose your connection, do any of the lights go out on the modem? Lemme break it down for ya
modem light config #1
-power
-cable
-pc link
In this case, we're looking for the cable light going out, blinking, etc.
modem light config #2
-power
-receive
-send
-online
In this case, we're looking for receive and send lit. Online won't be lit because this config always lights up in order and others won't light until all the previous lights are lit.
Those are the two major configurations that I can think of right now. If the lights listed go out, and power cycling doesn't work, you'll need a tech out to check the signal strength, downstream signal to noise ratio, upstream transmit power, etc.
If you lose your connection and the lights on the modem do not change at all while it's re-establishing a connection, a good 5 minute power cycle should help -atleast for now. But that's tell-tale signs that the modem is dying.
nik