I just wanted to add that I got dragged through the mud on one of these situations. First, they flatly denied my pay claim because they said they showed me in a non middle seat. I kept the boarding pass though, so I followed up with the assistant chief pilot. Eventually my pay claim was approved, but here's the kicker........ the extra money never showed up. You have to watch them every step of the way and make sure you're getting paid because they WILL try to F you out of it.