Reserved final price not binding ?
 

I made in March a reservation for this weekend. The total price which I got confirmed on my booking is 140 USD. The price on the rental contract shows now 190 USD! I did not realize that when I signed the pick-up papers.

Is a confirmed rate with Avis reservations not binding? Hertz & Co never change the total prices once they are confirmed.

Are you comparing apples to apples?

Post what specifically your reservation says, and post what your contract says. List out the line item details. Chances are something changed (like you agreed to an upgrade, changed the dates of your rental, used a diff discount code, taxes changed, etc.).

This happens to me from time to time. They charge me the right rate when I return the car.

Absolutely, I am comparing apples with apples. I did not touch the booking and did not agree to any changes at all. Total price changed from 134.01 USD to about 320 USD. Specially strange is the newly added "airport surcharge" (is "surcharge" on original booking) and the newly added "prepaid fuel" (was neither booked nor mentioned on the original booking").

You'e answereed your own question. Taxes imposed by government authorities change. When they do, your cost changes. As to the prepaid gas, you simply decline that (presuming you don't want it).

Don't let desk people or the fact that there's a line behind you stop you from double-checking the numbers. I always have a printout of what I reserved and know the total I should be seeing. If it's off by more than a few bucks, I hand the printout to them and ask what's changed.

Which you agreed to, presumingly. If you signed a contract when you picked up, there was a "FSO" or Fuel Service Option, which you have to check indicating which Fuel option you want (you can decline all). OR the agent asks you about fuel when you pick up.

Either way, as Often1 said - dont leave the counter unless you review your estimated charges when you pick up.