A few weeks ago, a user began to vandalise the wiki I administrate (Harry Potter Fanon Wiki), and despite my warning, said user decided to ignore it. Hence, I banned them. They decided to create a second and blatant sockpuppet account (they added two digits to the name). Obviously, I blocked it as well.
Once more, the same user created yet another account, and has returned to the wiki. Is there a way to permanently block them?