"Extremely rude phlebotomist"

I had an appointment in another department at 4.20pm and it turned out I needed another blood test so I got to phlebotomy at 4.30 and got a ticket but as there were a lot of people in there and it was hot I decided to wait on the benches outside. I could hear numbers being called so I thought I would be ok. Wrong, I find that after a few minutes someone had closed and locked the door so myself and another woman knocked on the door and were shouted at to go away they are closed. I showed my ticket at the glass in the door and the phlebotomist waved their arm away as if to say go away. I waited there until some of the public were allowed out as they locked them in and others out and said I was waiting outside as it was too hot inside and said that I already had a ticket. I was eventually allowed in but wouldn't it have made sense for someone to come out and ask if anyone was waiting for bloods before they just shut the doors. It was like their life depended on locking those doors. I just found the whole experience bizarre and not at all caring, yes it was the end of the day but we are all hot and tired and not one of the phlebotomist had a friendly smiley face they all looked really miserable. Also there was some animosity from them because I walked in but all I'd done was take a ticket and wait on the bench outside it was their fault they couldn't be bothered to check to see if there was anyone waiting outside. I just feel they should have some manners and not be so rude and dismissive.