Xbox 360 Live Account from Child to Adult Help?

ok so my little brother was making my xbox 360 accout when we first got xbox live. i recently turned 18 and i figured i would be able to promote my account from child to adult but when i tried to, it still thought i was underaged because my brother put HIS birthday instead of mine. so now that im 18 i STILL cant download mature content over xbox live. how would i fix this? I WOULD PREFER A PHONE NUMBER TO CALL. there has to be a way to do this. i just need to know what number to call. creating another account is NOT optional. PLEASE HELP!!

Suggestion:

1-800-4MY-XBOX

Tagged as: xbox live child to adult