We arrived back about 3pm on a Sunday afternoon. It was very busy as I assume a number of flights had landed together. Unfortunately there only appeared to be one member of staff on duty in the office, when I went in to get my ticket validated I commented on how busy it was and I could hear the assistance buzzer going, she said she had not had time to answer and see what people wanted. I got back to my car and went to leave the car park to be met by what can only be described as gridlock at the barriers. For whatever reasons the barriers would not open for people who had inserted tickets, they were pressing the help button but no help was forthcoming. It must have taken 20 minutes to out through the barrier.