Club Sites full

I was interested in booking a pitch at Baltic Wharf for November /December but found that the site is fully booked for my dates, I tested the booking system and i can book outside my dates without paying any deposit. In view that this site is always full why not take a non refundable deposit , this will ensure that those people booking the site intend to use it. and will allow otjers who are genuinely interested being able to book.