Paid and extra £12.50 to upgrade from the long stay car park to the short stay car park only to find my ticket wouldn't open the barrier to let me leave at 1.30am in the morning, I then had to reverse from the barrier, re-park and walk to the office at the long stay car park to get the attendant to adjust my ticket to open the barrier and walk back to the short stay car park, in all probably a longer walk than I would have had to make to retrieve my car from the long term park, £12.50 wasted. The reason given for the barrier not opening was that the camera must have been unable to read my number plate as it was a private registration.