I've been having quite a number of reservations on BOOKING.COM but only One of the people that reserved actually showed up. I've just received an invoice from Booking.com to pay a fee for people that didn't show up, what solution is there because I cannot pay an invoice for people that didn't show up
You should be reporting, via the original booking page of each guest, all no shows. If you have no means of charging the guest yourself you should also select the waive-charges box.
This will remove the booking from the invoicing system.