The difference between the wizard's head and the cherry picker is this. That the cherry picker is controlled by a computer. And it doesn't go up unless EVERYTHING falls into the right place. Keep in mind that there have been far more times that it went up then didn't so you can guess how reliable that computer is. But still.
The situation with the Wizard's head is something that is controlled by a person in this case the actor. The actor had to be there at the right time and wasn't.
Frankly I don't think either of them warrant a refund/exchange.
By buying a ticket to the theatre you have to realize that there is a small chance that things won't always go as planned and you just sometimes have to deal.
I know that there are some shows that have a backup plan that are very technical. I know that in Les Miserables. If the turntable didn't work for whatever reason. They continued the show concert style.
And, the last thing I have to say is that it is different to have a Marquee name in the show and to give a refund when they aren't there. By giving someone above the title billing it is the producers way of saying come see this actor/actress in this particular show. When they aren't there then they have to give you a refund because they promised you that they were going to be there. They don't show up you get a refund.
I know that many of the tourist theatre goers aren't as understanding as the people here in terms of a problem with a show. Either technically like the cherry picker not working or casting like the above the titled billed castmember was out that night for whatever reason.
But, there has to be a limit of what is understandable and what isn't. It's live theatre. Tourists have to realize that mistakes are part of live theatre and they can't expect a refund every single time there is one minor thing that goes wrong.
Even if I paid 70 bucks for a ticket and there is above the title casting in the show that i am seeing. And even if the person is out I don't complain. I use that as a chance to see the understudy and get a good performance regardless.
"If you try to shag my husband while I am still alive, I will shove the art of motorcycle maintenance up your rancid little Cu**. That's a good dear"
Tom Stoppard's Rock N Roll