Pi Box piece too thick
I just received my RPi starter kit, and began by assembling the Pi Box, but I noticed that one of the horizontal plates (Top/Bottom) is apparently too thick to fit into the slots in the sides. If I place both top/bottom pieces side-by-side, one is noticeably thicker than the other.
I have a file on hand, and theoretically I could file the plastic so it could fit, but I've no experience with modifying acrylic plastic, so I don't know if that's actually a good idea. Obviously I wouldn't be opposed to receiving a new part.
So, what's the recommended solution to this?