I agree, it's not worth making someone lose their job over something like that but in the future, if it happens again, it may be worth it to get their boss involved and just say hey, this is both extremely rude, immature, and bad customer service. I understand though that in the moment sometimes you just want to get out of there. While it sucks, just remember that most people are understanding and it may surprise you. The other day I was picking up a food order and the guy giving it to me was this hard looking dude who worked in the back but he was very patient and said "no problem at all" when I told him I stuttered.