Reserved a car a couple month's ago, to drive from Vegas to Phoenix. Went to Dollar last week to pick it up, and the clerk told me they didn't have the car I reserved available... Now I've experienced this from Rental agencies in the past, they try to up-sell to a larger (additional cost) model. When I told them I wanted the car I reserved and already paid for in full.
Basically was told 'tough shit', either take the compact car we have (downgrade) for the same cost and cram the luggage for all 4 of us into it, or screw up your vacation trying to find another rental agency. (they didn't say it quite like that, but you get the jist).
Bottom line, don't rent from this location if you want what you pay for.