I assume your response means you are not an admin.  As I have said to the other party involved, you are promoting a very unfriendly wikipedia.  Accidentally changing one number in a year, or one word (when an inexperienced user thinks they are in sandbox) is not vandalism.  As a representative of wikipedia, you should be nicer to users.  If you feel this is vandalism, you should report it to an admin, not act on it yourself.