I downloaded mine via bitorrent. Thats what I do for all my favorite British shows that take forever to come to the US. Seriously, they just got around to selling the series 1 dvd in the US, let alone the second series.
It is however, extremely illegal so it can easily get you in BIG trouble if a movie studio (usually blockbuster movies) catches your ip taking one of there films. So be careful what you dl or else you'll be made to pay $2,500+ on a settlement fee.
youtube for season three episodes but they are in parts only proplem here is the first episode part one to help you find the rest they are all made by the same person