'Can run it on ultra' and 'should run it on ultra' aren't quite the same. Before I upgraded my GPU, I 'could' run several things on ultra, but performance was for shit, and it would cause crashes.
You'll need to provide a bit more detail on what constitutes 'super glitchy content' and that 'legit' setup before anyone can help you.
If you're after a refund, this isn't the place to post the request. You'd have better luck going through the service you bought the game from (Steam, GoG, etc..) This forum is for technical assistance.