Hey So I recently started a peaceful server with lots of builds and we were just having a fun time. I enabled some command blocks for some fun builds when this guy called Gypsyjazz begins spamming "mob bombs" of some sort and spamming foreign characters in the chat. Then I banned him. HE JOINED BACK AGAIN and filled the world with lava. I banned him again, and then he joined back and banned ME!!! I unbanned myself in console and banend him and joined back but he kept banning me. So I tried stopping the server and putting up a watchcat. Did not help. I turned off command blocks. Somehow he was able to keep unbanning himself. Now I can't even start or stop the server anymore. Please help and ban this guy. He destroyed a really good server. He was also hacking other people's messages and portrayed as me and started spamming the N-word, along with some of my friends as well. What should I do? I feel really devastated.