I got all 3 of my discs off, the front ones were ok, just one that rounded off so cut a slot in the head of the bolt and used an impact driver with flat blade screwdriver head to remove it. The back one was a bugger and only 2 bolts came out ok, tried the method I used on the sticky front bolt but the heads split in half and half of the head went flying. So I used a chisel and hammer on the half of the bolt head remaining and tapped it around until it came lose. Needless to say I'll be replacing all the bolts when I put the discs back on!
Chris