Well this didn't quite go to plan. Staff had no idea of the 'free earlier or later flight' and it didn't show on the flight conditions. But was clearly displayed on the app terms. Tried the app where 'flight change' button was clearly visible next to boarding pass button once check-in was open, but threw an error. Tried calling & twitter (could share screens) before, as a last resort, going to terminal.
Finally, the customer service rep at AMS put me on standby list 1hr before departure of earlier flight and I was able to board (20+ free seats).
Staff were very good, wasn't their fault. The systems didn't show it as eligible and their back office team wouldn't permit the change. Was recommended to pay fare difference and submit a complaint, not quite what I was after.
I've another similar ticket in a few weeks, hoping I don't want to use much of the flex!
Last edited by The doomed; Sep 29, 2019 at 9:13 am