Rear Caliper bracket 2001 S3

[richyo]

Hi all, I'm refurbishing my rear brakes on a 2001 S3. For the life of me I can't get the caliper carriers off.
I've tried spline, TX, triple square and hex to remove the bolts. It's a recessed fixing.
The only thing I haven't tried is a ribe bit.
Can anyone confirm what I actually need before I spend some more money ?
Thanks
R

 

[A Banging Donk]

8mm hex I think?

 

[richyo]

Thanks - will try tonight