Extra person turning up

An additional person turned up to stay in one of our lodges- as we have an inclusive price here which includes use of the kayaks, an full animal encounter, firewood etc then we set our prices on a 4 person basis so if an additional person comes then they are charged separately. The guests lied and said they were only 4 not 5 so how do i get booking.com to charge for the additional guest as on the booking.com form it says 4 people only