Originally Posted by
canadiancow
He was checked in, but the phone agent also mentioned that, and said that even if he cancelled the check-in, I wouldn't be able to do the upgrade. Maybe I should have had my friend cancel the check-in (can you do that with checked luggage?) and then phoned back, but after that second call, I had to run to catch my own flight.
And he said "24 hours", not "same day", although who knows what the restriction actually is
FWIW, United's site says 24 hours, but Swiss' site says they can be done up to 3 hours prior to departure.
Can't know for sure about the 24 hour rule - but I am confident that the fact the (s)he was checked in ruined this for you. Unfortunately you also can't cancel check-in with checked bags unless you have friends (ie. you are friends with the concierge in a certain city).