[ROVERNET - UK] P6 Brakes - even more ??s

[phing]

Hi
 I've decided to remove the diff to get at the rear brakes . I can't move the bolts securing the drive shafts to the discs . So far 
I've used penetrating oils , extensions on socket wrench ratchets , and a DeWalt electric impact wrench,   with no results . What's 
the next step ? Heat , it's a bit close to the fuel pump and piping ? Clever applied violence using jacks and ring spanners ?? Is it 
possible to shear the bolts if I try too hard ?
 As  always any advice will be welcome
Cheers
 Patrick