Who / where do i send in a report for issues with these forums?

Which forums are we talking about?

these ones https://forums.xbox.com just select report at the bottom of the post

or these ones http://answers.microsoft.com under the post select the 3 dots, and then select report abuse, and continue from there

have you tried go to activision and verify forums, sometimes sites send emails with patch, updates, etc to customers who report the issue...

[quote user="jbits22"]Since my friend is unable to report this hacker and myself sending a complaint won't do much, I don't know where else to turn to but the forums. [/quote]

This I don't understand. How is it that you can not report them, but you expect strangers on a forum to report them? How does that work?

You're completely wrong when you say "myself sending a complaint won't do much". Sending a complaint via your console is exactly what you should do. The complaint will go directly to people who have the ability, the tools, and the motivation to ban people
like that. http://forums.xbox.com/xbox_forums/xbox_support/f/26/p/19139/121140.aspx#121140

Posting in the forums is the completely wrong thing to do. Your post here will do not a thing to ban that person.

I expect is was phone support who told him that.

Phone support seem woefully ignorant of the forum rules and continue to send people where to report, seemingly oblivious to the fact it can get them suspended from here.

You can report them through their profile, however, since those types of attacks are done through your internet and not Live, the enforcement team may not be able to do anything. They can only issue enforcement actions for anything done on Live itself.
You may want to contact your ISP to alert them of the issue.