Sorry to hear that. When I was still running just a shield I had the Brukus Shield Shackle along with just about everything else they make. What's that saying about an ounce of prevention?
If this is a true story (pics would help validate) then there's one bold a-hole out there. Did you have bike parked in lot where their CCTV system might've caught something...??
I remember once when wife and I went on vacation and came home to find that someone had totally rearranged all of our furniture... Total professional job and we actually liked it better than we had it before.