Absolutely, terms and conditions (such as subject to availablity) should be on the voucher. It is not abnormal for mere mortals (aka non jetsetting FT members!) to make holiday plans more than 3 months out, and wanting to be able to confirm your hotel before you book flights is reasonable in my mind. If the voucher came with those restrictions, a) it should be stated in advance of the bids and b) be on the certificate. I would be tempted to contact someone higher up in Four Seasons (or, maybe just try the number again, and hopefully get through to someone happy to make the booking - it is a stratagy that works well for me with the airlines!) and state that the T&C on the cert do not state that (it is possible they do issue certs with a 90 day clause, and ones without perhaps?)