My sister's flight last friday night from JFK to LHR was cancelled due to mechanical problems. It was the last flight out and she didn't have time to make the American flight. Apparently there was no offer of other flights at the time and the lines were horrible and she didn't feel like messing with that situation so she just went back home.

What are her options in terms of demanding compensation for the cancellation? Also I'm sure she's due a full refund for her ticket, but shouldn't she get at least $400 or something like that?

Thanks