How to ban user from posting?

Hello!

I am searching for a good way to ban a user who is bothering me on my site.

I know I can "block" him by checking it in user settings. I don't think this is a good solution. He gets a message he is blocked and he can always open a new account.

I would rather have something that automatically unpublishes nodes or comments submitted by the "bad" user. In this way he will hopefully think something is wrong with the site and this will discourage him from posting. Even better if his nodes are visible only to him and invisible to other users.

I thought I could do this with the actions module but I did not find an option to unpublish items by specific user or user role. Or maybe there is a module for what I am trying to do?

I would apreciate your ideas! Thank you in advance.