Poor customer service!!!

I really need help!! I've contacted booking.com on at least 6 occasions now and I haven't heard anything back. 

My minimum night stay is 3 nights but guests kept booking 1 night stays. I've checked the settings serval times and everything seems fine but this keeps happening. Now I have 3 guests that I want to cancel as we don't accept 1 night stays. 

Can someone please advise me on what I should do? I tried cancelling 1 of the bookings myself and booking.com wouldn't allow me.