Oh, let's close this thread - now I'm getting flamed by the Californians. I hope that those who visit the US get better treatment. Having flown for a living since the early '80s, I've got to admit that this was the worst service I've seen from a major airline - but hey, I guess complaints about bmi aren't actually allowed on the board.
I'll continue to fly UA, where at least to my untrained eye, loyalty does have some advantages. BTW, I've flown about 2/3rds of the *A carriers and gotten primo service on all of them (even the bmi folks were nice - not helpful).
I'm sorry for all the posters who don't get treated a little better by UA personnel here in the states. I've found them to be remarkably flexible and understanding, with the exception of some of the ORD and LAX GAs.
I've also learned it's better to book an earlier departure and use a Monty Python-type excuse "sorry, there was a cock-up on the M4" or "had to re-route because the tube station was closed for security reasons," if you miss your flight.
Ah well, no plans to visit the UK any time soon - we'll see what evolves.