Booking.com ****

I booked rooms on booking.com and when I was about to confirm my booking the residence said they were fully booked yet when I told them I already paid via booking.com they said they have not received any money since they were fully booked. I proceeded to book 2 other rooms but I received the very same problem. I was left stranded. I told them I want my refund and sent countless emails yet I still haven't received any feedback or any assistance. Booking.com is a ****