Blue Waters Hotel and their booking.com ****

I made a booking through booking.com, for the 16th of December. I have a medical emergency that forces me to be in surgery on the 16th. I called the hotel and they told me I need to be there on the 16th or forfeit my three-night stay. Today is the 12th, they could still make the room available for someone else and move my booking. but they told me they cannot make any changes to the dates. I offered to send medical documentation, but they made it clear they would not help. they could not answer me when I asked why they have this option available on booking.com if they know they cannot give the right service their customers. this is a ****, as long as there is time to rebook the room to someone else, they should allow me to move the dates. i did not even want to cancel, just move the date. I asked for a manager, they hung up