So this is now my second time and with the puzzle locks from whom ever Ford gets them I have noticed this happen : First time with my 05 GT the dealership were about to rotate the tires and the key was (cold) was in the trunk SNAPPED .
Now this morning I was taking them off so they would'nt have to the key teeth all shattered what the "F" metal fatigue or cold so Do order a second key and do not over crank them when on the wheel.

 

it took a few wacks , but not to overdo on the 3/4 " metric socket over the lock then used a ratchet to turn slow , sometimes having to rewack the socket for a better bite, again don't over doo as you don't want damage all of 20 mins to get them off.