My wife spends money without my permission; what should I do?

I have already taken away her driving privileges for previous spending transgressions, and now drop her off and pick her up from work, but I discovered that she went shopping with a co-worker on her lunch break. She bought a new bra, claiming the old ones don't fit since she started nursing, which may be the case, but the point of the matter is she did this transgression and needs to learn her lesson, so I took the bra back. What else can I do help her understand her place as a wife and woman?