Had trouble locating the correct car park and entrance - directions were not great. The proximity to the airport is good (easy walking distance), but the barrier cameras do not work very well at number plate recognition. The cameras at the entrance barrier were not apparent, and did not recognize my number plate. I was issued with a standard (non pre paid) ticket. I used the call button to confirm that I was in the correct car park and was told that my prepayment was valid and should have been recognized on entry. We were told to park using the ticket issued. On leaving the car park on return from holiday the exit barrier took my ticket and asked for £270. I again used the call button and the operator again confirmed that I had prepaid, and then opened the barrier. Hence what should have been a simple operation was marred by poor number plate recognition.