My little brother has been playing a lot of Lego Marvel Superheroes and he has perfected it to 99.8% completion but it glitched so he can't complete it fully. The only achievement he does not have is the "complete the game to 100%" one. I talked with support and they told me to contact the Advocacy team through here. Would it be possible for you to unlock the achievement manually for him? His gamertag is k1ckb4ck 487.