I do understand how this feels like bait and switch. Sadly, AA has the CoC going for them, and the most AA has to do is refund the cost of MCE for the lost seats.

I believe it is possible a FAM grabbed your seat(s). While I understand they generally operate from the front cabin, I believe I have read (although have zero actual knowledge) that on occasion they operate in pairs with one in econ somewhere. IF that is the case, AA cannot comment to you.