This is the way ahead:
Just say to the Manager - it'll be cheaper to replace this spanner than replace one of those large shopfront windows come Monday morning.
But don't let him call your bluff. If he doesn't replace it pop down the local park and give some Chav £20 to go and pan the windows.
Then visit him again and say, Are you going to replace this spanner or is this going to be a weekly occurance.
My money is on him giving in. Maybe not the first time, maybe not the second, but definately by the 7th or 8th you'll get a new spanner.
Posted on another Forum by a Copper no less! Respect!