Originally Posted by
wysiwyg
The overall trip is flexible, meaning I can cancel or change anytime and free as long as there’s no increase for the new flight. So I called yesterday and asked to be moved to the following day’s flight out of CDG on the return segment (shows the same price if I price it individually), but they still wanted around $800 Cdn for the change. Too bad. My layover is already ~19 hrs, (arriving from Tokyo at 19:20 and my next flight to Toronto is at 14:05 the next day.) so I was trying to extend it for a second night
Of course there's a fare difference; instead of booking TYO-YYZ,departing on Day X, you are changing your ticket to TYO-CDG on Day X, adding a stopover of >24hrs, followed by CDG-YYZ on Day X+2.
Breaking your journey in this way means you have to use different fares - you are no longer travelling direct (though not non-stop; that's an impossibility on AF, but any layover of less than 24 is "ignored" in this context) on a TYO-YYZ ticket (which has its own special TYO-YYZ fare) which was available for your original ticket, but you are now explicitly asking for two different journeys; TYO-CDG and CDG-YYZ, each having their own (different, and higher) fare.
In your original ticket, the night in Paris was an unavoidable outcome; you may actually really want this, and have chosen AF specifically to be able to see Paris, but as far as AF is concerned, you are only interested in getting from TYO to YYZ and you are travelling from one to the other in the shortest possible time, and most direct way, that AF can provide. All that changes when you "tell them" that you actually want to spend extra time in Paris, by deliberating building in a second (otherwise completely unnecessary) night in Paris. You are no longer a traveller only interested in getting to Toronto (and who was offered an effective discount due to the inconvenience of a forced overnight stay in Paris en-route, when you could have booked a direct option with another airline), you are now a traveller who wants to see two destinations - Paris AND Toronto - and can be charged more accordingly.