I can imagine the terror stricken lady's feelings.
usually I wait in my sons' cars while the other go for shopping.
I always make sure my window is slightly open and I am connected with the outside world and not hermetically sealed inside a steel body.
One day I forgot to keep the window open and even before they had walked to the entrance of the stores, I started suffocating out of sheer panic and started jumping like a drunken monkey inside the car.
Both the phones were with them. I could have passed out but for my power of telepathy. My son sensed something was wrong and came back to the car. I was saved from a sad end due to sheer fright!