Same thing just happened to me.

Rented at KOA on Friday, returned yesterday. Oddly, there was actually someone at the return line to check in while I was there. Said I'd get an email. I didn't.

Called the 800 number, they told me they don't have a record of me even picking up a car, do I have the RR #, which I don't (I accidentally left the receipt I got at checkout in the car, so I don't have it anymore). He offered to email location, but then thought, if they don't think I even used a car, why should I go through hoops for their antiquated IT that can't even figure out I did.

Figure that either KOA is sending in the info. on Island time, and I'll get something in a few days, or I'm treated as a no-show and got a free rental courtesy of Hertz's well...I'll be nice...not great...IT. Any reason to worry either way? Or should I follow up with local location. I figure I did a bit, at least, of my due diligence by calling in.