Update: Got a locking wheel nut today........walked in local MB dealership in work clothes, they looked horrified as If I was there to hold them up Said could I try your locking wheel nut keys on my XF as I have lost mine, they seemed puzzled and said this is Merc only we don't cover chrysler here....I then went into explain the birth of the xf mode (seem to do this quite a lot lol?) to which they still looked puzzled but got the parts guy to come have a go with his set...and badda bing sixth nut in we had a fit....£27 and a few hours for new one to be delivered and I now have the holy grail of my my missing wheel nut, refurbed ally's here I come