Similar problem. I have ~3000 points, looking to book a 1-week Premium car. The site will allow a 1-day or 2-day rental at 675 or 1350 points, but nothing more. I have had a rental this year: I don't believe any of my points are subject to expiration before the target award rental. Also does not appear to be a rental partly overlapping a blackout date...

I'm tempted to click first from the rewards list to generate a PC, but what happens if for some reason it isn't accepted? Do the points remain in my account until I finish the reservation using the PC?

I have no desire to phone Hertz. If it comes to that, I'll just rent from National.