More bloody problems !!!!!

I can't get the fan off my 2.5td 90. The 4 bolts that go into the pully have sheered off (can't see why) how do I get the fan off ? I have a spanner that fits but the hole lot is spinning, how can I hold it to flog the spanner to get the fan off. not bothered about doing damage to the fan as a kenlow is going back on.
Thanks.

Are you undoing it the correct way, fairly certain a 2.5TD (along with most other LR's) has a LH thread?
Normally just shocking it will do the trick, yes the viscous unit will spin but it is the shock that does it, not a steady pressure.

Iv'e hit both ways, no joy!!