I booked through Hotel.com. I changed my arrival date through the Hotel.com app a few days before I arrived. I also received an email confirming the date change as well as confirmation number. However, when I arrived the hotel, they couldn’t find my booking. They only had the initial arrival date. Also, it indicated another booking app (instead of Hotel.com). Notwithstanding this, the hotel managed to make a fresh booking for the night at same rate. If they were fully booked, I may not have been able to get a room.