Person using fly hack in visitor survival

Okay, really simple, I was about 30,000 blocks away from the spawn and I only allowed admins and my friends in real life teleport to me. One of my friend's brother pushed him out of his room and accepted himself a teleport request. The first thing that caused the chaos was that my friends brother let his friend teleport. At first is was easy to get rid of him. I used flint and steel to kill them because they were griefing. Next thing I know spamming teleport request. So I built an area of stone walls, it was about a 5x5x6. I put lava at the bottom and stood in the middle so they would die. Then they started using nodus fly hacks to get out. So I put a roof in. They still were griefing then I killed them with flint and steel again. Then they start breaking my teleport-kill-area- type thing. (they set it up to were they can tp to me anytime they want) They flew in a hole with no items. So then then start breaking the walls while flying, I broke it and replaced it. Then they got bored and went to HG and hacked there to start with full iron, diamond sword, and flew around. ( I don't have screenshots of the HG time period because I was fixing my house due to hacking griefers.) The names of the hackers were BrassDuck, and Wildfire52.

Please remove these people from this server-Or at least from survival and HG