Anyone have experience with Enterprise forcing them to upgrade at additional cost?

I had a reservation this weekend, for $17 per day. I chose the lowest rate since it was just for a few days while my car is in the shop. The rate was something like "we choose the car" or "manager's choice" or similar verbiage. My reservation receipt says “Vehicle Class Vehicle determined upon pick-up (Compact or Larger) or Similar”. When I got there, the car lot guy said he didn't have any in that car class and could only put me in an intermediate. He refused to honor the price on the reservation saying "that just means compact and we don't have any on the lot right now." The new price is $28 per day. I would have gone elsewhere since I don't like giving my business to those with shady practices, but it was getting close to noon on Saturday so I needed to rent something.

Does Enterprise have some sort of policy that allows them to do this? I can't imagine it wouldn't be a violation of some false advertising laws or something. The car is to go back Thursday morning. Should I try and press the issue upon return or just contact Enterprise Corporate by email after I return the car? I guess worst case scenario I have the reservation confirmation so I could always just file a chargeback with my credit card company, but every other car rental place I've worked with usually provides an upgrade for free if they can't honor the existing reservation. With the lot being as full as it was, and them only doing carside reservations (no one was allowed into the building due to the pandemic), I can't imagine they couldn't find SOMETHING to put me into and I'm guessing the salesman was trying to get some sort of commission for an upgrade?

Thanks for any ideas you guys have on how I should proceed!