I've called and they waived a fee for me (cheapest tix). Told them my assistant made a mistake in my travel (called minutes later), and that I was hoping you'd waive the change fee for me as I found a flight (make sure you have the flight no.!) for a little bit less (the difference was 5-10 bucks). After I gave them the flight numbers they said "please wait" and the CS rep said the supervisor said it was fine this time and to enjoy your flight.
Might have something to do with my status, but I didn't mention it; just said a mistake was made.
YMMV