While i understand you are trying to help out a friend, you topic title, and your replies contradict each other. You claim a friend was on his account, but then say he was only on his laptop. Sharing an Account implies they are on your account, not on your laptop/computer while on their own account. So if he was permaban on the first offense then more than likely it was because someone else was on his account. If not then there is something he isnt tell you/us.
Also note that Riot doesnt have a Support Hotline, or a way to call them. If you want to contact them you either need to do it online with their support page, or (not too sure about this though) you need to actually go to the headquarters and talk to them personally.