Oops, I never answered your question about a course of action...

Hertz has it written into their contracts and terms of service that they are in no way liable for consequential damages due to not having a car for you (even for prepaid and guaranteed reservations). So it is highly unlikely that you can recover any money from Hertz for your issue.

As for a charge back. I thought Hertz didn't give you a car? Did you prepay? If not, then what money did Hertz take that you can charge back?

Edit:
Oh, I guess you mean the rental that you finally received later... I wouldn't do a charge back on that rental. You did accept the rental and the rate along with it, so you legally owe the money on that rental regardless if whether or not you feel that Hertz owes you money. You will certainly lose and be blacklisted from renting with Hertz again.