Having booked on line and followed the instructions I found upon attempting to exit that the barrier would not lift as it was demanding £72 for an over-stay. I had been parked for about 30 hours. I pressed the button and the person I spoke to asked for my reference number which, luckily, i had to hand. He then opened the barrier BUT a queue had formed behind me as one of the other barriers was having a problem too. Clearly the technology isn't working correctly,. Meanwhile, my sister used the VIP parking service which was excellent. She had a flat tyre and the people helped her pump it up. They were awesome,