It sounds like he removed more than he needed to.
I'm not convinced that it needed routing at all.
The way to fix this is to try some different,
full length shims until you and he can agree that
the neck height is correct.
Once you have determined the exact thickness needed
then make a one piece , solid, full length shim from
maple, ash or some other hardwood to permanantly
glue into the pocket.
That will give the neck correct height and a solid
foundation for the neck.
Basicly reversing the over routing and letting you
somewhat pick the depth you want, without a bunch of
loose shims being stacked up and potentially
damping vibrations between the neck and body.
If done right, it should be as good as new.
It will take time and patience to get right.