Everyone:
Thanks for your support thus far.
Here's an update: I called ATA Customer Care yesterday through relay. Sorry to say this, but a moronic lady answered after a loooonnngggg hold, and said that there was a complaint form on the website. I explained that I prefered to speak directly to a live person, and she grudingly asked what my complaint was. I explained to her the whole story and what happened. Guess what she did? No apology. She said that she would have to refer me to the ADA text, then read to me a LONG string of "legalse" - basically that the ADA requires people with disabilities to be reseated, and that seating is not guaranteed. When I felt that she was not the right person to talk to, and asked for a supervisor/another representative, she said the office was closed and she was the only one (excuse me - it was afternoon, even in the East Coast). She then said goodbye and hung up.
Sigh. Any suggestions, etc? I know this isn't a BIG DEAL, and probably not worth fighting for too much, but I do feel that treatment I received wasn't right.