Urgent help needed

[flyingflea]

A friend of mine has sheared off a bolt which holds the rear anti roll bar on and you can not get anything to grip the remaining bolt.

And tried drilling it but he managed to break one of them inside the bolt.

Does anyone know if these have a castle gated top or are they threaded all the way up?

Any ideas more than welcome

Thanks car is a 2002 HDi saloon