Rear anti roll bar clamp - snapped bolt

[Pskey28]

Hi all

I am trying to replace the anti-roll bar bushes on the back of my 2002 hdi estate, the bolt has snapped , how can I access the top of the bolt to drill out and replace ? I am assuming it is inside somewhere ?

Is it rear sub frame out ?

Any help, picture etc.. Would be appreciated.

Many thanks

Paul.