*sneeks in for a brief moment* Humbly offering a suggestion...

The worst punishment that Sir gives me when I am deserving is when he gives the "cold shoulder" and ignores me for a certain amount of time. This, to me, is the absolute WORST punishment and I have never made the same mistake when receiving it.

When in public, may I suggest, sending her to the vehicle to wait for you. When you get there, tell her why you are disappointed with her, and then letting her know what her punishment will be and for how long. i.e. "You will not be seen or acknowledged by me for 45 minutes because of your conduct." I can't imagine this not working with anyone.