I have experienced a problem using my second 40 euro voucher (from expedia.fr). After I entered the number of the voucher, the system showed that this voucher had already been utilised. Finally I tried the same voucher using another e-mail account (not the one that I used to refer my friends)and another credit card, and everything went fine....kind of weird..I got the feeling that expedia.fr system restricts one 40 E vouchers to one account/CC, which is not the way it is supposed to be.
Also, can anyone explain why the expedia.co.uk refer-a-friend page after enetering your e-mail account and password for refering a friend, turns into expedia.fr (and the result is that the voucher is in Euros, not Pounds)?!