How do i remove M10 bolts Peugeot 307 1.4 2002 for front disc replacement?

How do you remove M10 bolts (star shaped facing into car) in order to replace front discs. I have removed upper and lower m6 bolts and removed calliper and can replace pads.
Do you need a special tool ? I have a T155 X 140mm socket bit for Torx Fasteners but it doesn't move !!