We pre booked and on entering the car park received a ticket with our correct number plate. On leaving we inserted the ticket but the barrier did not open so assuming we had extra to pay ( our flight was late) we put in our debit card and left. On checking our bank statement found whole amount had been charged twice. Had rigmarole to get a refund but I imagine many people don't even realise they have been charged twice. Lady told me it was our fault because we should have waited for barrier to open on entry rather than press button for a ticket and on leaving when the barrier didn't open we should have gone to the office ( we would have been very popular blocking the exit) Why doesn't the booking confirmation contain instructions and/or a warning about this, I suspect it's a nice little earner perhaps trading standards could audit their books. Otherwise bus service fast and at least the car was secure.