Mk 2 Focus - removing sheared locking wheel nut

[thinkofaname]

I can't get one of my locking wheel nuts off because the head of the nut itself has sheared off. The nut has a rotating outer collar, so I don't think that those reverse thread tools, or the method of bashing an old socket over the nut, will work. I have heard that there's a tool called Dynomec which can remove these kind of nuts. Anyone know of a garage or tyre place in the SW London/Surrey area which has this equipment?

[rumple]

Ive used the socket method on those type before, use an impact socket and hammer it well on, if it doesn't work you've lost a couple of quid, then go to a garage.

[thinkofaname]

Right, so you mean that bashing the socket on compresses the slip collar against the nut?

[neiljohnson]

Often welding a bit to the broken socket is the easiest way

[thinkofaname]

Well, I took it to a garage where they had the Dynomec kit.
After an hour, they gave up. Didn't charge me anything, and they even gave the car the statutory cursory wash, so at this point I'm almost ahead. They have ravaged the wheel nut, though, and the collar is no more. All that is left is a scarred stump that vaguely resembles what the locking wheel nut used to look like.
Tomorrow I take it to some bloke who swears blind that he will definitely get it off.