Through some testings, it seems my router cant block MAC address with wired connection. I end up blocking all possible IP addresses with firewall, except for mine. Glad that works.
My router is actually at the common lounge and he had his PC set up there to plug to my router through a wire. While he wasnt at this PC this morning, i plugged out his internet cable and put a note on the router.
If he still insists on trying to steal my goddamn wifi, ill chop his balls.
If you control the router you control the traffic.You should be able to setup ACLs depending on the router but if it is a low end router you could just curve his traffic to anyplace you want with static assignments. I use to play jokes on friends a while back by routing their traffic. For example you could setup www.google.com to go to www.onrpg.com
Also you could turn off DHCP and set a static IP to you mac.