Problem encountered on exit - ticket not recognised so screen indicated that we owed £100+ even although we had pre-paid. Pressing the Help button did not result in any assistance first time around so we had ring contact number for advice and were told that the ANPR system had probably not worked although the Reg. number appeared on our ticket. Following this contact we then had go back round system again and wait for response from Help service - thankfully this worked ok this time. Once the Help service responded we were able to exit but took 10+ minutes to resolve the problem.