Double booking!!!

Just got a message now saying the place we booked for easter has been taken. We booked a flat in Port Edward 2 weeks ago and used out credit card details to secure. The terms and conditions stated we needed to pay by 31st March. We were also in contact with the owner all was good till this morning. We are 4 different families from different provinces getting together for the Easter holidays and now we are told that one of the places we booked is taken!?? Were must we now get another place wen everywhere is booked out. How is this possible that we reserve a place and then now without giving us the option we are told that someone else paid for the place???? This is double booking and I've never experienced this before. What are we supposed to do now with the other places we booked and they cant accommodate us all??? Is booking.com so *********** and unreliable as well as unrealistic?? There is no contact number to call anyone to enquire only and email adress???