Fast Park. On arrival process was quite straight forward even without help from friendly staff who were on hand to help if needed. On return process was easy and straight forward until I tried to exit and gate would not open with ticket provided. I was expecting some kind of additional payment as I was 24 hours late (flight issues), but it was unclear how or where this would happen. Having been told how to exit Fast Park, it was not until I got to the main exit that it became clear that an additional payment was required. Extra payment not the issue, it was the lack of clarity of where and when that was the issue. Something within system that may need addressing. Forgetting late issues, overall experience was good, and I would definitely use again.