Hertz - Downgrade when exchange problem rental

Last week, I rented a midsize and during my rental, the car A/C stopped working with burning smell. I drove to the nearest hertz location to exchange, and on the phone I was promised to exchange to same class, but when I arrived and it was downgraded to compact. Should I get addiontal discounts or compensation for downgrading?

The Hertz customer service is very good. Call them and I think they will give you a credit/discount.
On the other hand, I would not have taken/excepted a smaller car for exchange. Why did you?