Everything was fine until we came to try to leave after a concert along with a number of other people. In spite of having prepaid and being well within our time we still had to queue to get an exit permit at the machines, one of which was not working at all and the other appeared not to be working properly. The help number was useless and that led to people queuing to exit in their cars and pressing the help button once at the barrier. This then took 15 to 20 minutes for each car to be allowed to leave. This resulted in fraying tempers after a long day and customers helping themselves to exit. A complete nonsense caused by lack of staff; it seemed to be pointless prepaying. You must be aware of big events happening in the vicinity of the car park and should staff it accordingly making sure things are working properly so that the number of people leaving such an event at the same time can be on their way ASAP.