The woman was being abused by a male person that looked more than a foot taller than her, clapping in her face. And continually speaking over the top of her.
I would have done what she did and asked for a refund from the other staff member.
That male staff member then acted like they were the manager and denied her a refund or the service she paid for. The other employee was standing right there and did not intervene at all.
So, failing that there seemed no one else there, that this staff member had the authority to deny service and demand she leave without refund, who do you think she could have gone to?
Sorry, my immediate reaction to a very tall man yelling at me without a break and clapping at me very close to my face is to raise my voice to be heard to say anything. Even sorry would have been yelled to be heard. Fear would be feeding my reaction also, with arms waving and then the staff member standing in a position I felt blocked my clear exit.
How great though that you feel you would have kept your calm in the face of that reaction.