before you impose traffic limits you need to provide a way to monitor the traffic you use as well as setting sensible limits for each tier, providing burst traffic speed costs the isp nothing its just the amount of traffic you use that cost's the isp money, someone on a 1mbit connection using 1 gig a day cost the isp the same money as someone on a 150kbit conenction using 1 gig a day, so in reality we been ripped off.
Also take note of the problems we having at the moment in the broadband section of this site, seems random points of the net are going offline for ntl user's at the moment
also take note of the ongoing problems with the mail servers (months for me) and the dns servers.
There is no way you can mention that ntl are doing this to remian profitable so they can keep their network up to scratch because the fact is the network isnt up to scratch, and another fact is the bosses got a fat bonus.