At current, we turn off online booking for this and let all staff know to not book the service but this is not an elegant solution. If there was an option to suspend the service so that it could only be booked on a future date going forward, we wouldn't lose bookings of the service and it would force client and manual booking to only occur when supplies are replenished. If a warning occured when booking that stated, supplies for service not available until xx/xx/xx and only allowed booking after it, this would save two birds with one piece of bread :)