I sent my letters off.

You all might wight to double check on who they have as your U.S. Representative is. Mine was wrong so I had to find the correct one. Sending a letter to the wrong US Rep is like sending the letter to my Grandma, it would be received but not taken seriously.

Are any of the other airline unions doing anything about this?

If they are not doing anything now is the time to write your union and tell them do actually earn their dues.