Someone arranged one with me half an hour before my league match yesterday, and 2 hours 20 minutes after the league match I had my CL second leg. I tried to cancel it but it said the FA didn't allow it, then after the scheduled time, it still showed me less than 1 minute. I also removed him from my friends at about that time so it showed no team at the top of the page where it usually shows your next match.

I logged in just before my next match to find that the game had actually been played. Luckily, it was an easy enough league match, and I won both my competitive matches yesterday. I would be very pissed if that happened before today's top of the table clash.