Complaining here won't do a thing.
Let you thoughts known at
http://airconsumer.ost.dot.gov/escomplaint/es.cfm
I just did, echoing that I think it's an unfair practice that AA charges a fee for transaction it does not allow to take place online for free, and urging the Secretary to exercise his duty under
49 U.S.C. 41712 "Unfair and Deceptive Trade Practices" and cause AA to stop it.
Incidentally, the DOT just did this in the case of AA involuntary denied boarding vouchers (same issue--they couldn't be redeemed online so were subject to the fee which the DOT termed an unfair practice).