I have posted about this years ago (literally). When I first bought a 360 when first released, I signed up with a gamer tag of Ultimatequinox, and used an .fsnet email address. As some will know, freeserve died ages ago, taking my chances of receiving a password reset (as I cannot remember it anymore).
So I have a tag with tons of downloaded stuff and a respectable gamer score since 2006 which I can no longer use - all because of the password. And of course I've emailed various people here, and at microsoft, all coming back with the same response of answer these security questions (that are years old, like the bank card used at the time and so on) which I can't answer. All thats needed is a reset, just one, so I can get back into the account and get my tag back and make use of all the money time spent on it. But microsoft and xbox live cant help me beyond the generic responses - this needs someone specific - anyone out there? Thanks!