Axle bolts

Hi can anyone give me some advice please.

I have a 1970 VW Beetle and have been replacing the front axle beam. In taking the old beam off I have managed to break a couple of the axle bolts in the frame head. Is there a recommended way of getting these broken off bolts out?

I suppose in the absence of better advice I would try to drill out and clean up the threads with a tap but I am a complete novice at that.

I think the bolts look like an M12 thread, is there anything else I need to know?

Thanks

That's not good at all. I suppose there isn't anything left to get a vise-grip onto. Heating Before turning is advised. If you have to drill be carefull. I've seen people use nuts on the backside used with longer bolts.