Unprofessional Services from Booking.com

We made a booking last Friday and payment went through. Saturday morning we received a call that informed us that there was a double booking and they would refund our money. This is very unprofessional and we had to find another accommodation for that evening in Cape town !! All of the places was fully booked as there was Tennis and rugby that weekend. We found a place and had to pay more than triple of the original amount just to have accommodation for the evening . I will not support Booking.com again. I have tried to contact them Via mail and phoning and i only received automatic recording responses i Could not get hold of them.