FWIW, even if they show availability and you can book, they may not have a car. Only time I've ever shown up at a rental car agency with a reservation and no cars was with Hertz. Basically they told me tough luck and nothing they could do. This was pre-pandemic too and simply due to bad inventory management. Up until pickup, I kept getting reminders about reservation but when I showed up, I was told that they had been short cars all week. Though the system showed full availability for booking.