How do i get my outline to align with the building I've modelled?

I received a new building outline for a building I've already modelled.

I replaced the outline on a constant known point so i could make changes, saved and opened the model in hevacomp.

The outline is no longer inline with model for some unknown reason.

I've then measured the distances from the outline shown to the model in hevacomp from a known point by creating a room so I can move the outline in autocad to the coordinates of the room in hevacomp. 

Notice the line going from the top right corner of the building to the corner of the model in hevacomp and that same line autocad.

I then moved the outline (keeping the datum lines in the same place, in autocad to the point where the model should exist. Which lead to results shown below.

I have tried several tried several different ways to get the outline to align but all results show that the model moves and therefore does not rely on the coordinates shown in autocad.

Which makes it impossible for me to align my new first floor drawing and continue with my project.