i had this problem once, it was an ORD-LAS flight flying out of LAS at 12:05AM or something like that... I wanted to leave on a MOnday midnight so i can get into Chicago in the morning and go to work but i stupidly made a mistake and booked Sunday midnight instead... I called twice, AA didnt care (and i was an EXP), and i also tweeted a message for this honest stupid mistake that i never done before... Fortunately the tweeter team showed goodwill and changed my ticket without any fee... Anyway sorry for the long reply, but maybe try tweeting them if you have one, i find them very helpful...