If by any chance that is in fact an "hacker" which i doubt, another fail comes on the way.
Unless that ISP (TalkTalk) uses static IP addresses for their clients you are in fact blocking nothing, as a simple reboot to the router/modem implies in most cases a change on the IP address!
One other thing, asking to MWG staff to handle your problems, by tracking down the possible user, how lame can that be?
Sorry, but if you need to do that, you should not even consider calling "hacker" as it seems you have no idea of what an hacker is!
Well, seems you do have someone that somehow does not understand what is and what not!