As KeaneJohn has mentioned, the BAH Duty Office, IMHO, is worth its weight in Gold. I had a disrupted BAH journey last year and I very much doubt I would have got it sorted as easily by hanging on the phone for hours to try and get someone at BA to answer. Email to Duty Office who responded very promptly and alternative flights arranged. Home pretty much on time, so I was very happy. As was SWMBO!