You
must first send a notification to Microsoft by the form of a mail to Weston, the guy in charge, explaining that your work is wrongfully displayed on that page, that bethesda has no rights to your work, much less XBox.com. You wait three or four days for a reply, send another notice, and in case nothing changes start a legal action on the courts of your country.
You can also start outright an action on the American courts, using a US lawyer legal advice, but you might as well wait a bit, that's expensive.
I forgot, at the same time you send the notice to Microsoft also send one to Bethesda PR, since Bethesda owns the rights of the stuff posted on the XBox site, and that's clearly outside of what they send, for sure.
Pete Hines, +1-301-354-4274,
phines@bethsoft.com, or Erin Losi, +1-301-354-4207,
elosi@bethsoft.com .
Hope it helped.