Don't get me started on Booking.com!
I booked a hotel last minute, grabbed a pizza, then when I went back to the app to check the hotel's address was greeted with a message that the room was no longer available. As it turns out because I was the one who had booked it, but leading me to think that the booking had somehow failed, despite being previously confirmed.
I booked the next available room (at a higher cost), and headed to the hotel.
When I went to check in, I was told that I had two rooms, but that I couldn't cancel one because it was past the cancellation window, and to contact Booking.com. Booking.com said it was up to the hotel, despite the double booking being caused by their shitty app UX. Wise.com (who I love for transfers, but shouldn't have used for this card payment) were powerless to help.
tl;dr Don't use Booking.com. I'm just glad it was only a one-night stay!