Before you return it, do some testing on tripod in good light to see if the lens is the problem. It would be even better if remote shutter release is used.
this. when i first got my 85 II, i shot a casual event with it shooting wide open the entire night.
when i got home, i previewed the images on a screen and found all of it to be hopelessly out of focus.
propped it onto a tripod and ran it through a battery of tests with MLU on center point - turns out i sucked shooting @ 1.2
i installed a focussing screen that helps make things snappier at larger apertures and makes manually focussing possible with such extreme apertures as well. manual focus is still tricky, but now possible.