Originally Posted by
darthbimmer
I thought that if you wanted to change a ticket booked in a discount class like S you had to pay a sizeable change fee. What am I missing?
As
United737522 mentioned, itineraries can be "refared." What this means is that after you buy a ticket, if the price
of the identical itinerary drops, you can get the fare difference credited as if you had bought the lower fare (the credit is either issued as a travel voucher, for nonrefundable fares, or your choice of voucher or CC refund, for refundable fares). This policy is essentially intended to encourage early booking (or, alternatively, to
not discourage early booking) because you aren't "penalized" if the fare drops after you purchase.
There are no change fees in this case because you are not changing anything about the itinerary - the dates, times, and routing all stay the same - but rather exchanging your (old) higher-fare ticket for a (new) lower-fare ticket on the exact same itinerary. Change fees apply only when you are changing the itinerary (dates, times, and/or routing).