I was there 7-14 September and had no issues . The barrier raised as we drove up, although to be honest because we have used on several occasions in the past I had not paid attention to email so was still expecting a ticket to issue for use when leaving. We were therefore a little concerned about getting out on 14th however when leaving the barrier was fully up so we just had to drive straight out. .

Unfortunately it didnt seem plain sailing for all as when we were walking from car park to the departures on the 7th we were stopped by a lady driver asking what to do as she had pre booked and barrier wasn't lifting. We told her system should recognise registration and perhaps she hadn't been close enough to barrier and to try again but as we walked on I saw her still having problems and reverse out. She had also been trying to scan something which I assume is the back up your are referring to but it didn't seem to help. She was in a southern reg car unless that had some bearing on it although it shouldn't really.