I was in a similar situation a few years ago. At the one day festival run by Radio 2. So not a place where you'd expect aggro. I'm also female and only 5'4".
Festival had signs on the way in and in the queue to the bar to say that to prevent waste, you had to pay a deposit for a branded hard plastic drink glass, which you'd reuse at each bar visit and could either return at the end of the day for a refund, or keep it as a souvenir. No problem.
I get to front of the queue and find myself next to a towering bloke, buying 6 pints. Young girl, aged about 18 says it's £72. He thinks he's misheard and she said £30 is a deposit for glasses, and tried to explain about the scheme. When he starts screaming in her face, he's "not fucking paying any fucking deposits, who the fuck did she think she fucking was? Thirty fucking quid... "
I'm rarely rendered speechless, but literally nobody at the bar, or behind it stepped in. As I was next to him, I gently touched his arm, and said, "C'mon mate, just listen to the girl, you do get your money back, she doesn't make the rules... " He span round, loomed over me and started screaming in my face, he had red face, spit flying out of his mouth as he demanded I ".. mind my own fucking business, you nosey fucking cow!"
My knees were knocking, but a crowd was watching (fuck knows we're security were) and I summoned some confidence and told him to back the fuck off and that the young girl didn't get paid enough to deal with vile wankers like him, and added "get your drinks and fuck off!"
Some other blokes in the queue started to gather round him, letting them know of their presence, he slammed his card down, paid and stomped off.
The poor girl was so shaken, she kept saying sorry to me?!? I was shaken up too, and pissed off nobody else stepped in.
So, sorry for the long reply, but good for you, wanted to share my story. And although I absolutely abhor bad manners, bullying the girl was totally uncalled for. Well done.