Do you need the Jag? If not, I would have Roadside bring you another car. Then ask for a partial refund if they bring you something lower than your reserved class. Not sure of any other option as I would NOT drive a car that cannot hold coolant. If you do, and damage it, you could be at fault since you knew of the issue.

Unfortunately, getting someone on the phone at a large location is basically impossible. If you're pres club or chairman, those agents can help, but otherwise it's probably unlikely.

Regarding your reservation of "Select", "expecting some sort of Jaguar" and receiving the F-Type: What was your actual reservation for? Avis has many "Select" classes (XE, XC90, E class, GLS, Vette, Denali, etc). Instead of cramming everything into the F-Type, you could have asked for something that was in your class "or similar", as this series notes.