I have done customer service, and I have heard the phrase used by a customer; though not at the same time. The only time I actually heard someone say “do you know who I am?” in a customer service capacity was a random dude ahead of me crashing out at 7-11 over $0.05 because the asshole couldn’t do some simple arithmetic. He claimed to know the owner and threatened a bunch of shit to the teen behind the counter, holding up the line for like 20 minutes. And in a very “that happened” moment, when he finally fucking left, half the people in line literally clapped.