This happens a lot and I absolutely HATE it.
I'm working with a customer. The issue takes an hour or more. No, I didn't create that situation. I didn't make our location fail to have stock in what he wants. I did not cause one of our other locations to take over 20 minutes to answer the phone. I DID choose to handle other customers while waiting. So, you Ms. Customer show up at minute 35 and when I go back to this customer to assist him - YOU are the one who knows that I am supposed to assist some other guy first? Well this happens all of the time, so I take in stride and explain that no your guy was not there first.
You repeatedly told me that this other guy was supposed to be ahead of him. No, I replied each time, he was not before him. Finally, I further explained I have been working with this man for over an hour. I am NOT doing the wrong thing by working with him now. Just because I tried to be efficient by taking other customers in the interim. Another associate intervened by saying the gentleman YOU were championing had been working with her. OK, no problem but that did not render MY course of action inappropriate.
So of course you very Christian self loudly proclaims that this is stupidity. Cause why should it simply be true that you just WEREN'T THERE when my customer first arrived???