If you are talking about pari-cz, without even looking I'd agree with you. He should be investigated at least. I remember him doing this all the time in the past as well.
But also bear in mind that admins don't need to notify you about the actual action they take, and pushing for an answer is not a good idea. Sometimes players have just too many accounts, or play from different places, its not really a 2 minute job at times.
Anyway - I had a "blacklist" back at the day, not sure if they use it or not, but his name is there.
If you are talking about someone else and not about pari-cz disregard this reply.