Rear license plate mount missing?

Hi, this is my first post but I've dropped in to spy on this place a few times since picking up my little orange baby in July. I could go on for days about how much I love driving it...

Ahem, I'll move along. Someone stole my rear license plate yesterday while I was at the store. Yay! 24 hours and $16 later, I'm free to drive again with new plates. I went to put the new ones on and I think there is a piece missing. There are no threads to put a screw into. Holes, yes. But there is nothing for the screws to bite into. I'm thinking that the thief also took a piece of my SOUL.

I "fixed" it with wire. Super classy, I know.

I was wondering if anyone knew what the plates are supposed to mount into. I'm going to had to the dealership thursday but I like to know what I'm getting into ahead of time.

Thanks!