As is normal practice in these types of situations where a maid is running the bookings, they will accept every booking.
They do it on the basis that there will be no shows and late shows.
Irrespective of punters being disappointed, that's the way they manage to cram in the maximum number of bookings for the SP. The practice won't change, because it works better for them than keeping slots tightly allocated.
You were just collateral damage.
You did yourself no favours by being late. Savvy punters know to arrive early, and have a plan B&C minimum.