I used this form : http://www.francebillet.com/contact.do
maybe you can try this link: http://www.fnactickets.com/contact.do?_lang=EN
I used this form : http://www.francebillet.com/contact.do
I used that form, got a confirmation email immediately... and then a day or so later I got a reply with an address to send my unused tickets.I used this form : http://www.francebillet.com/contact.do