The manager or owner and the employee who booted the ambulance should have been arrested. The boot should have been taken by the police and impounded. The city should bill the store for extra time wasted dealing with booted ambulance. They should also also bill the store for any repairs needed to the ambulance.
I would also say some Ted Poe justice would be in order. Once convicted, the manager and/or clerk needs to be posted at a high traffic corner carrying a sign saying “I am an idiot. I booted a city ambulance.”