Originally Posted by
canadiancow
No, you have to pay, and in theory, you have to pay ahead of time.
Technically, if you no-show a flight, you forfeit it.
Last time I did it me meetings ran late I missed my flight. I went to the counter, they charged me 75$ + tax for a same day change and put me on the next one. I booked flex G and ended up rebooked into flex H.