On the whole,the experience of pre-booking was ok,worked out cheaper than paying on exit.However there were a couple of things I was unhappy about. On arrival at the car park we were very lucky to actually find a parking space,good job we weren,t late or in a hurry,just happened to find one on one of the perimeter fences.A parking location would be nice when you pay in advance.The second thing was,on exiting the car park we got to the barrier I put the ticket in and it said I owed £53.Absolutely livid,its very embarrassing when you have to back up with several cars behind you .Luckily the office was next door and they cleared the ticket.Would use this service again and hopefully won,t have this experience repeated.