
to the forum
Is this person on an ntl connection? If not, then there is little that the abuse team can do to help you- you are best off filing a complaint with his service provider and they will take the appropriate action. Include as much evidence as you can- firewall logs, emails received etc etc.
With regard to changing the ip, are you using usb or ethernet?
The long and short of it is that the guy is blackmailing you -> pay me or i'll break your internet connection, so have you thought about contacting the police?