Wolf 300TDi, R380 transmission mounts problem.

I've hit a wall getting these brackets undone.
The AESP 522 blithely states that I should "From underneath the vehicle remove bolts (Fig 1 (1)) securing left and right hand mounting brackets to gearbox.".
All well and good, but they are not moving, even with another ring spanner on the end of the 19mm.
Steel into ally strikes again.
If I could weld (but I can't) I'd weld a ring to the end of a bar.
Given all that, anyone got any other method of getting them out?
Heat doesn't seem to be an option with a silicone seal only an inch away.
The transmission is supported by a jack.
Any pointers very much appreciated.



4.4 Take

Unfortunately with these things where you suspect steel into aluminium corrosion, there's no easy way around - its a matter of either you have great luck and it comes undone or bolt head shears off. In the future, put in some studs and hold them down with nuts instead.