Bumping this rather than starting my own thread on it because I am seeing the exact same thing happen to me on a one way rental in Germany I have next month. My total on my confirmation email is 270 Euros but when I check in on it now it is showing up as almost double that. I called Hertz and after a few transfers the rep basically told me "bring a printout of your confirmation email and be insistent"

Anybody else run into this? Or can the OP give an update on how it turned out for them?