Here's the thing...
If they paid it to you by mistake, you're gonna have to pay it back.
While you don't know if it was a mistake, you're not going to spend it, even if you need it.
Maybe call and see what it was for? That way at least you'll know, and you guys can either use the money, or if they are due it back, and you choose to jerk them around, the jerking can commence full speed.
The "not knowing" thing just sucks. A phone call isn't helping them a bit. It may help you guys, though.
