There's a thread up on the Dope about how you should respond if you see a small child alone in a car on a hot day, in a mall or supermarket parking lot. This is something I have literal nightmares about. If I didn't see parents around I'd be trying to break the window very fast.
A lot of people thought this was foolish because walking to the mall and finding security would only take a few minutes. Many were afraid of being sued for trying to break a window. I think you should look for parents, call 911 if you don't find them, and tell the 911 person that you are breaking the window now. Walking somewhere could take five minutes. On a 30C day by the time you got back the kid could have asphyxiated or died from heat. This is not a time to worry about lawsuits.
In slightly less depressing news I should be cleaning or packing right now, but I'm not. I'm sick, it's been a heck of a week, everything is a bit messy but not horribly destroyed, and I deserve cider (thank you, Stuart, for leaving the cider! I love you in a platonic and chaste way!) and slumping on a chair while on the internet, and an early bedtime. I really hope Nat doesn't have screaming hysterics tonight.