Board Thread:Support Requests - Community Management/@comment-452-20141015211337/@comment-14310002-20141015222735

Hi. You should always warn a user before blocking them. However,

" What happens to the badges of a blocked user?
 * Users who have been blocked from editing will have their badges removed and will vanish from the leaderboard (if they have been on there). Once the user is unblocked, their total badge and point count will be returned. If they are still eligible for the leaderboard, they will return there as well."
 * Help:Achievements 

That should help you deal with this problem. I have talked to many users that have been banned due to cheating the system. I wish you luck with this case!