I don't think anyone will do anything with it.
Yea because there is a slim number of users who know what they are doing.
@OP, you cant do anything since you are not computer savvy.
Even if you were, you can only hit him offline or report him to his ISP.
Also, without law enforcement, you can't get any personal information regarding him or the owner of the IP other than a broad map from certain IP location websites which will give you a bout a 50 sq mile radius to search
Edit: Secondly, his ISP is in a different country, so forget about it.
RuneScape has no customer support, you cannot recover anything.
Word of Advice: Quit RS, if you REALLY need to game, play WoW, but that still sucks