The GA made an honest mistake, 'fessed up to it, you kept your original seat and got $100.

People make mistakes, that's just life. At least in this case you didn't get scr*wed because of someone else's error.

A long time ago, I was flying MIA-SFO on AA. In those days planes still had smoking sections and I obviously did not want to sit among the smokers.

AA gave me a seat assignment in smoking but told me they would try to accommodate me.

At one point, the lead flight attendant comes back to me and asks me to follow him up to a seat in non-smoking. Then he must have blanked out as he walked me right up to first class.

Realizing his error, he walked me back to coach, but by this time AA was boarding standbys and not only were all the seats in non-smoking filled, so was my original seat.

Despite my protests, I was told I was the one who had to get off the plane ("what about the standby in my seat, for which I have a boarding pass?")

When I raised a stink they threatened to call the police, so I got off.

The kicker? When I got to the service center and explained what had happened, I was told I had voluntarily gotten off the plane, and that my ticket was thus void.

Since I was flying home, I was forced to buy a full Y one-way ticket (which was some seriously big money).

They even threatened to charge me a "storage fee" for my bag at SFO (which didn't happen, of course).

Ahhhh, AA at MIA...well known for its touchy-feely customer service.

You did OK

P.S.: As a million-mile flyer on AA, after a series of similar incidents on the airline I simply stopped flying AA.