How to handle a staffing issue?

I'm second in command at a local haunted attraction. Every year, staffing is one of my major issues. It never fails that someone always calls off last minute.

This time, I was given advanced notice that one of our main actors would not be there tonight. I found a replacement who seemed very excited about the idea, but his only answer was maybe. Now, I can't get in touch with him. He hasn't answered any of my text messages or phone calls.

Would it be fair to replace him since I can't contact him? I don't want to replace him in case he shows up on his own. But, at the same time, what if he doesn't show and I have no replacement? He knows when and where to be, but I just don't know if he's going to be there. I'm worried that he will come on his own and then I'll be the "jerk" when he's replaced and has no pay because I couldn't get in touch to make sure he would be there.

So, my question is... Should I replace my replacement since I can't contact him?