Punishment for this kind of magical crime is to have that same crime inflicted on the criminal. The Fairy Kingdom is a great believer in rough justice (and argue it is better than no justice at all). This is one of the few attitudes in the magical realm my awkward fairy godmother Eileen has always agreed with. Certainly there is no question of any other kind of justice being offered by Eileen herself.
Punishment is inflicted by senior fairy godmothers such as Eileen and Hanastrew though most groups organise their own for their own. Let's just say it pays not to be a witch who offends the Chief Witch. Life expectancy is greatly reduced!