Nigel Hamish Murch

I have beaten all of the levels in Halo 4 Master Chief collection, first run on legendary, but have not been rewarded with the achievements for beating it on all difficulties, the individual levels say completed on legendary, Please can you help 343 to fix this as xbox customer support staff said wait 75 hours and I should have them but its been 5 days, I phoned support and they said only 343 can unlock them, and that both New Zealand and Australia are having this issue.