How to get a refund from Steam?

Hi guys, 
 
I would like to get a game refunded to me by Steam. It's a pre-order and it's before the release date, so it should be possible. 
I just can't find any contact information (I'm in Europe btw).
 
Any help would be appreciated! 

 http://forums.steampowered.com/forums/showthread.php?t=1117862 
This was posted on the steam forums and seems to tell you everything you need to know with regards to cancelling pre-orders.  It sounds like a bit of a process to get everything sorted out, but as long as you're not cancelling like a day before the game comes out, your request should be accepted. 
Good luck!

Thx guys!