I recently "won" a certificate for a Four Seasons stay at a charity silent auction. I went to the FS website to confirm that they had availability for my desired time (approx. 7 months hence), then called the number listed on the certificate.

I was informed that my room could not be reserved at this time, and that they could not guarantee that any inventory of complimentary rooms would be available; they instructed me to call back within 90 days of my desired date. No such policy is enumerated on the certificate itself, only a note about "subject to availability"; as I said their website confirmed that they have rooms available.

This does not strike me as behavior becoming the "#1" luxury chain.

P.S.: I won a Ritz Carlton certificate at the same event and made my reservation with them without incident.