Some similar happened to me once on AA. My company asked my to delay my vacation by two days and booked me a new ticket (full fare coach I think) for the SFO->MIA redeye. When I arrived at the airport, well before the flight was leaving, my aisle seat was gone. The flight was overbooked and apparently they decided someone else deserved that seat more. I complained, but all I got was a center seat in the exit row.