I would suggest a visit to the shop as your description is confusing (No offense meant). The ring gear and bolts are hitting which case? The Housing or the differential itself? and which bolts? the Ring gear?
How can that be? The ring gear goes on one side, the bolts on the other.
the ring gear bolts are on a much smaller radius than the OD of the gear.
I am totally confused ( which is not unusual LOL)
Further more I would not allow him to start HACKING on things until the issue is identified and corrected PROPERLY.
Keep us posted