FNAC has me FRUSTRATED. I am a regular on line buyer and used to jumping through the hoops, but the FNAC site collects all the info and then states that I should stop by their store to use my credit card! I'm trying for a ticket to the Monet show at the Grand Palais in September.
I was just looking at this event myself. Try the Grand Palais' homepage:
http://www.grandpalais.fr/en/Homepage/p-617-Homepage.htm
Scroll down a bit you can "Book now your tickets for the exhibition coming soon!" which brings up this site:
http://www.digitick.com/claude-monet-ile-de-france-css4-rmn-pg5-fi1155.html
FNAC does reserve the ticket for you (and take your money), but you do have to stop by one of their stores for them to print out the ticket for you. It's a weird system.
Success! I've got my ticket to a special retrospecive exhibit of Monet at the Grand Palais. Thanks to all!