Avis employees who can't seem to close out reservations.
It's generally accepted at Avis that you can drop off the car without waiting for an attendant to check it in, walk away from it, and they'll close out the reservation and you'll get an email receipt. At least for people who have Avis Preferred. Sometimes I'll do that, either due to being in a hurry to meet my flight, or weather (like yesterday).
But now, on 3 separate occasions, they have forgotten to check the car in. So I've had to call them. And apparently now it'll take 2-3 days for them to fix the mistake and get me my receipt, so I might as well hold off doing my expense report until I get it.
Grr.