Well you can always try. Print out screen shots of any MMB pages you might have had, or booking confirmation emails, OLCI boarding passes or boarding pass stubs and a current summary of your account from ba.com and explain the situation in a very non-grandstanding way and you might find a kind soul who will take pity on you "just this once". In that case, run directly to the bar and ask for a glass of champagne which is kept behind closed doors in the Terrace. Otherwise it's a burger and a beer at Garfunkel's I'm afraid. Good luck.