Originally Posted by
FlyerJ
And, no, there’s no way to do a same-day change via the app or web-site — at least not yet. This has to be done in person, at the airport, on the day of departure.
I have twice in the last year made flight changes by phone (gold support line) the day before my flight (albeit within the 24 hour check in period) at no charge (because of status). It doesn’t have to be same day and in person, for golds at least