I had a ford locking wheel nut and it was impossible to remove. Tyres places, my mechanic, an engineer bloke all had a go and no luck.
The nut was to cwide in the whole and not deep enough to get anything on it and dig in.
In the end I took it to Ford and paid 40/50 quid to have them remove all the wheel nuts lol!! apparently I couldn't just buy the nut, they had to have it in to see which one it was.
Not sure if yours is a factory job, but was less hassle to cough up than try and remove it.