Well, I would have been royally peed off. 

Very hot weather, with a baby in a hot underground car park probably dead still, no breeze.

when you are waiting, that 9 minutes seems a long time.  This is one thing that really gives me the irrits, people who think they are more important than other people.

I would have given her a serve as well.  Would have well and truly stewed on it in those 9 minutes.  

as Amy said, she only apologised, and not heartfelt, shouted as running to car.  Only because she was busted.  She lied about how long she had been gone, trying to trivialise her actions.

i tend to agree with making a strong enough statement to her to make her feel it was an unpleasant interaction and not a good idea to go  locking some one in again.  Who knows, that might just even be the way she always parks.

as for Amy swearing in front of her baby, he is still that, a baby.  I hardly think he knows what she said.