I would write a letter and send it by USPS, maybe even certified. I had a situation, wrote a letter, and received 25,000 for each member of my party. AA could have written this off as "weather". Here is what happened:

1). Light snow with a total of 4 inches for day at ORD. Arrived from BOS
okay. 400 departures and arrivals cancelled that day (April 2007)
2). Departure (ORD/HNL-Flt. 73) delayed 2 hours for deicing
3). Flight cancelled for mechanical and crew time after deicing.. Secondary
warning device was the mechanical. They spent too much time arguing
about international crew versus domestic crew (they were debating on
flying aircraft to LAX). By the time the decision was made, crew time
limits came into play. Flight cancelled.
4). Rerouted ORD/MIA/LAX. LAX/HNL/KOA next morning. We were
originally in first class on flight 73. Ended up in coach from ORD/MIA but
back in first from MIA/LAX then to LAX/HNL. Then we missed our orginal
MIA/LAX flight but caught last flight out of MIA to LAX. Arrived LAX
around midnight. If I did not mention to the AA rep on the phone about
my original first class tickets we would have never flown first from MIA
to LAX. We were automatically rebooked in coach.
5). Spent night in terminal four at LAX.
6). Next morning talking with other passengers from our cancelled flight, when
they arrived at LAX they were put up at hotel by AA for the mechanical
cancellation. We were offered nothing.
7). Arrived KOA next day tired but finally stress free.
8). Arrived back in BOS, no luggage. AA delivered it the next day. It ended
up apparently on a later ORD/BOS flight.

Granted one thing lead to another but I was very happy that all of us received 25,000 each for this issue. This is a brief summary of what I worte but I was straight forward and nice. I did not ask for the miles. I just stated facts.