From imdb:
On May 10, 1996, two teams of double glazing salesmen are racing to hit a sales target of £29,029 in twelve hours, the highest sales figure ever reached. With little warning, a violent storm strikes the motorway, engulfing the adventurers in one of the fiercest blizzards ever encountered by salesmen.
Challenged by the harshest conditions imaginable, the teams must endure blistering winds and freezing temperatures in an epic battle to canvas homeowners and earn their commissions against nearly impossible odds.