I am in the same boat as you are. I do believe its a design flaw because both rear studs on my exhaust manifolds are sheared off right at the manifold on both sides. Luckily, the remaining bolts loosen up easily and the broken studs can be backed out with vise grips. I think its a manufacturing defect due to engine shaking or something because like i said, the studs were not frozen in the head so I dont think they broke when someone tried to take them out. I do believe they snapped off during normal vehicle operation
Anyway, while I was removing the studs to take the exhaust manifold off, I could not get the egr tube to unbolt from the manifold, so I had to get creative and loosen my shock absorber so the stud would drop down in the hole, loosen my steering column so I could push it out of the way, and remove the EGR tube from the EGR valve at the intake manifold. I finally got the drivers side manifold off and easily removed the studs from the head. I also removed the inner fender plastic liner to have more room to work.
While doing this, one of my exhaust manifold to exhaust pipe studs sheared off as well so I had to drill it out and go to the hardware store to get a new bolt and nut. Just drill it out and put a nut and bolt through the hole and it will hold it well enough (probably even better actually!!)