See what others have to say but I would call Avis up and ask them if there have been any changes in taxes or fees since you reserved your car. If not, then ask what you need to do to have the rate changed in the system prior to your arrival (might need to speak to a manager). You shouldn't have to waste your time once you arrive at the airport to fix a rate you already confirmed. You may have to fax your copy to them as proof. Also, do you have the original email conformation? The link embedded in them takes you to a copy of your final reservation page.

Good luck and keep us posted