"car park security"

I was picking up medical equipment at was told on the phone by hospital staff to park at the front of the hospital as I was just picking up equipment. As I am also disabled I found a space at the front and displayed my badge. I picked up my equipment and I was only 10 minutes. While I was getting I into my car I noticed a security member of staff in a yellow coat, letting cars pass them and they were waving them through. as there is road works at the other end of the car park I assumed the way out was pass the security staff member. They were standing in the middle of the road so I beeped them. As soon as they turned around they starting shouting I was going the wrong way. They was leaning right into my car shouting. As a patient I found this disgusting. They had let others through and was laughing and joking with them. But their mood changed when they see I was a patient. I made a innocent mistake. If they would have spoke and explained I had made a mistake I would have said sorry, but I shouted telling them not to shout at me. I myself work in the NHS and would never speak to anyone like they did even if they were angry. I think they are a big bully and need to learn how to talk to people.