Hertz Rented Out My Automatic Car and Won’t Refund Through Booking.com

I booked an automatic transmission car through Hertz for my trip to Lesbos via Booking.com. When I arrived at the rental office, just 30 minutes late, I was told that all automatic cars had already been rented out because of my delay, leaving only manual transmission cars. Since I can only drive automatic, I refused the manual car and wanted to cancel the booking. Renting a manual car for the price of an automatic didn’t make sense either, as automatics are more expensive. Hertz directed me to cancel through Booking.com but then informed me that I wouldn’t be refunded. This is highly unethical—they rented my car to someone else and still charged me. I demand an immediate refund for the service I didn’t receive.