Rolling Roadblocks

Drove down the motorway to visit family today. Don't you just love lorries? Particularly the way that, on two lane motorways, you get one going at 50 mph and another going at 50.00000001 mph which pulls out to overtake. This means that you get to stare at a "Well Driven? Dial 0800 12341234 to let us know" notice on the back of the rolling roadblock as it sits in your way for 15 miles.

I wonder if anyone dares to dial that number? I think if you do a little red light comes on in the cab of the lorry in front of you, the driver looks into the rear view mirror, sees you talking on the phone and then taps the brake and twitches the steering wheel slightly to smear you and your car over around 800 yards of crash barrier...