I ban an user subnet (first 2 numbers of the IP) and them he just create another account with the same subnet, someone banned normally can still see the content of the site right? so how do I ban so that person can not enter the site at all or don't see nothing on the site at least??
Unfortunately, you can only block the activity of the visitors with certain IP addresses.
One user reported me that all his PMS disappear is that is possible? for inactive users maybe?
That shouldn't be possible. Perhaps, someone entered into their account and removed all messages. Can you ask them to provide a screenshot, or more details, in general?