Misrepresentation on car hire resulting in non payment of refund

Booked a car via them to tempest car hire. Booked unlimited kilometers and tempest confirm the booking with unlimited kilometers but refused to pay my deposit saying they don't have unlimited kilo on their side. They say it's booking.com problem. Booking.com cannot be reached to respond or refund my money. Very bad communication with this company with no accessible phone numbers. I want my refund