I played Halo 4 all last week. Saturday night I made it too the final level on Heroic. I saved and quit for the night, Sunday morning I resume my game and it starts me back on one of the middle levels. I restarted my x-box and tried it again, and it started me back on the same wrong level. So I started chapter 8 over again, beat the game and I didn’t get the achievements for completing the last level and for beating the game in heroic.
What should I do to get the achievements? Do I need to replay the entire game?