Booking Conflict



Can anyone help me with advice please. Actually we are very new at Booking.com and we plan to give a room on rent. But we got a problem. We started to setup our advertisement on booking.com and before everything is final we got 3 bookings and all are conflicting with our existing gusts. What can we do now? We could't find any online chat or email address of booking.com to contact with. What is the procedure to cancel any booking as a host? We are really in a mess, please help us. Thanks