Maybe the dealership can give you a temp tag while they sort the mess out for you. It should be the least they can do to keep you happy. Although it does kind of suck driving around with a paper tag.
I recently purchased a vehicle from a used car dealership. I was so busy flipping through the pages that I neglected to notice a fee for $500 with just a couple of initials next to it (mistake #1 - read EVERYTHING). I called the salesman and he told me that was a fee for a 30/1k mile...