With this method you can either Cancel the whole booking by providing the ReservationId or a part of a booking, if booking has more that one rooms/services by providing the ReservationDetailId. Both these details can be derived during the Booking Process (MakeReservation, PayReservation) or can be retrieved using the GetReservation
If the details is the last confirmed service, when canceling it all the booking becomes cancelled
CancelReservation always returns ReservationResponse with the latest update of the reservation and details