I dont have the recepit to hand, i was thinking of asking Ocuk to send me a invoice of the purchase
Drop CS a thread and ask them how to do an rma after you find the order number:
http://forums.overclockers.co.uk/forumdisplay.php?f=116
Log into your account on the store page and check your order history.
They will probably help you out by at least pointing you in the right direction.