Rusted bolts

[amwc]

Hi
I need to drill out some rusted bolts from a cast iron housing the bolts dont go all the way through though so I'm a bit worried about doing it myself just wondering if anyone knew who was the right trade to take this problem too?

 

[wotan]

How big is the cast iron housing?
could it be bolted to a drill press, if so this would make drilling far more accurate.
Mild steel bolts in cast iron don't normally rust solid, could you drill the centre of each bolt and use an 'ease it out'
an application of local heat might help.

Wotan