I am trying to replace the front outside CV joint on my '97 A6 Quatro. Every not and bolt I have touched so far has been grossly overtorqued by the guys who did some tranny work last fall. I am down to the #50 Torx bots securing the half shaft to the transmission. The only thing I can figure is that they us an impact driver to reinstall the bolts and damaged the bolts. When I try to use a brand net bit to loosen the bolts, the driver just won't hold. Seem the isnside of the star has been damaged.

Any ideas on how to extricate these bolts?