**from counter rep thread**

They have absolutely no business telling you that the reason your rental got screwed up is because of a car code error. That is way too much detail for a customer to handle, it is mind-numbing information for an employee to remember car codes let alone customers, and it is completely irrelevant to the customer because either way...Hertz screwed up. I'm sorry that they told you that. I didn't even fully understand what you were asking at first because I wouldn't have imagined that someone would actually tell you what they did - imbeciles...complete imbeciles.

It is easy to change car codes (classes) on reservations but as someone pointed out in your previous thread, the only reason they can't change the car code is because either:

a) The car class is already sold out
b) The location does not accept reservations for that particular car class