"I can't do anything." "That's not possible." "You can't do that." "Sorry, I can't help you." "You'll have to call Avis Customer Service. We can't do anything." Those fictions are all you'll hear from Avis, and you'll hear them over and over.
We heard them, repeatedly, in the Bellevue, WA office from which we rented. I heard them repeatedly in my six calls to customer service, who, according to the Bellevue office, would fix the problem the Bellevue office caused. Other commenters online have said the same: No one at Avis tells the truth, no one is competent, and everyone sends you to the Customer Service line, who say and do whatever it takes to take your money and get you off the phone. If you want to rent from liars and incompetents, Avis is your company. If you want decent customer service and decent treatment, go somewhere else.