Must be Singapore Airlines and / or Virgin. The latter (Virgin) are the most annoying. The website leads you to believe that the seats are available, takes you right through to completion and at the last minute suddenly announces that no seats are available. Calls to the Contact centre are met by useless and unhelpful staff who simply repeat that no seats are available. "But your website says there are". "oh, sometimes the website isn't updated properly" - absolutely pathetic. Singapore on the other hand never have BC seats ever