Snapped wheel nuts on Renault Scenic sport 2000?

Hi i have been riding around with three wheel nuts on.I took the car to a Renault garage to get the clutch replaced.When i collected the car they told me i now have 2 snapped wheel nuts but they wont own up to snapping the second.I took the brake calliper and disc off today to relise im no further forward.Do i need to take the hub apart to get to the snapped bolts.I have tryed to drill them out but the drill bits keep snapping anyone have any advice.