Find someone else to go to the ballet, she will not be going.

Whatever has occurred with her, I would leave what the relationship was in the past and not contact her again. If she contacts you, then you can possibly explore what happened.

You can ask for a refund of course, but I would also expect that since she did not ask you for prepayment this last time and you offered it to her, you may not end up getting any sort of refund.

Discussing with her the behavior/how to treat customers, etc. - I really wouldn't bother. If she contacts you maybe.