I had to change flights about 18 months ago due to a family bereavement, I was told that there would be a change fee for chnaging the flight ( I really can't recall how much ) however when the agent on the phone got to processing the change she gave a rather dramatic 'whoops, I forgot to apply the change fee, never mind, it's too late now'
I think as CWS said early in the thread, there are agents who apply their own discretion to whatever the rules are.