I, too, thought it was at the hotel's discretion, as the rep would always call the hotel to ask. But on a recent call, the rep said "since you're platinum, no problem" so I don't know. It's definitely come in handy. I try not to abuse it, but being on the road for the last seven months straight, I needed to do it a few times. But, can also confirm that editing the date to a later time works (think you need to do it in the app, since online it says "In progress". Didn't ultimately cancel it later, but was able to move it back a day.