Good luck trying to get 3 to 4Mbps out of existing Mobile Broadband networks, in real-world situations they often default back to something that has more in common with dialup than broadband. If you get between 500Kbps and 1Mbps on such systems then consider yourself to be very lucky.

Mobile this and broadband that, but the bottom line is BT's obligation to provide tangible service dropped in exchange for a buzzword-laden promise. Way to go.