Had a similar situation recently. Large Outdoors store w/big gun dept, 2 clerks working the counter on a busy Saturday, several time consuming transactions ahead of me, such is life. I was next, caught the eye of the clerk just finishing up w/customer and mouthed the words I'm next to him which he acknowledged w/a nod.
A guy butts in, grabs the clerk to get a gun on hold. 8-10 people around waiting, I protest LOUDLY I'm next, clerk responds he'll be w/me shortly. I was so po'd I walked out.
While driving home I called the store and told the operator I wanted to go as high up the food chain as possible. Got a manager who listened to me, agreed completely that my treatment was lousy, and took the clerk's name. He asked for my address, a couple days later I got a $25 gift cert in the mail.
A week or so later I was in the store, that clerk and I made eye contact, I asked him if he remembered me, he said yes. I told him How I'd complained, he told me he'd heard about it but still thought he'd treated me fine. I went on to tell him how his behavior had cost his employer $25. Childish on my part, being a little kid is fun at times.
Kevin