Now, I'm no lawyer, but it seems unless it's a actually a court decision to pay, then it's just a nice letter requesting you give them money. Of course they may just end up taking you to court if you don't pay, but that's a risk you may be willing to take.
It's probably just the loss prevention dept trying to recoup some of the costs resulting from the theft. Probably worth a shot on their part.
__________________
|