I thought they were doing it like orbitz when the price drops for the ticket in the same fare class they refund you the difference. Orbitz did it automatically and didn't need to call them. UA should not charge the $50 fee since Orbitz doesn't do it. I can understand if moving to a different fare class but not for the same fare class. It's also been my experience depends on the rep your talking to if they want to charge you or not.