Have you consulted with your GC and your architect to see what happened between the plan and the execution of the plan? One or the other or both will have a solution to fix this error.

We had a really bad experience with our original GC (and the architect was through them) - they are totally incompetent. We have a new GC who will hopefully have some ideas, but it wasn't their plan and design.

Yes, but it is up to your new GC to catch those errors and know what to do to fix it.