Are you using wireless? If so, try a wired connection and see if the problem goes away. If it does then you know the wireless link was the culprit.

If you're not wireless, then do what the other poster said and run a tracert whenever the connection goes crappy. It should show you the exact point of flakiness in the chain of hosts between you and CF.

If that flakiness isn't occurring with the first few hosts in the list (i.e. the ones under the control of your ISP) then complaining to your ISP will have little effect.

Once you do find out what hosts have the problem, there are ways to get the email address of the right person to contact.