Despite pre-paying I have had to ask the attendant to let me through the barrier by intercomm on the last two consecutive. Your system doesn't recognise pre-payment automatically at the exit barrier. Rather it asks for payment. So I assume you are trying to con me into paying twice. If true, than shabby treatment, but not as shabby as the airport itself. What a worn out under-invested ill maintained dump! Welcome to Liverpool? I don't think so...