Has anyone had problems with getting the gamer points for achievements completed on Xbox Live? Mine started out fine, I got a few including the 5 grenade sticks okay, but in the past 2 days I've gotten 3 killing frenzies and 2 mongoose mowdowns and still haven't received the achievement and points. Xbox support said they couldn't help because it was a "game-related issue". Does anyone have advice on how to fix this?