Well my first port of call would be fords, as its std.
If you get no joy with the dealer (which you wont) then ring ford CC and play
up merry hell, and I mean hell.
Id threaten them with watchdog etc etc, and it will be the last ford you ever buy.
It wouldnt be the first time ive heard of CC at least paying 50% of the cost of
repairing an engine out of warranty.
You have nothing to loose by trying
Just put the std plugs back in, even if one has melted