The work of putting on a new subframe assembly is actually pretty straightforward if you have a lift and the tool. Its only 6 bolts if memory serves.
I never put mine on because being from the rust belt the first bolt we tried simply wouldn't come out and being its a boxed frame we couldn't risk is breaking off as there would be no easy way short of cuting into the frame to fix that.
That one bolt was partway out before we even tried.
So the spot that bolt was to secure we welded on.
I still have that bran new uninstalled subframe lining around.
No idea if they will take it back, its been many weeks.