Just because he got banned wont do anything to the ISP and your game. Is your firewall on? Do you have an exception to allow SA:MP connection? If your using any download programs like P2P programs or torrent software, you have to stop seeding and close those programs. If its happening to people you know and use the same ISP and live in the same area, the ISP might not be working well at the time. Companies face many problems and maybe its just temporary.