Its all guesswork, unless someone's pulled the dipstick (assuming the car has one, getting rare now) and found no oil at all, no one knows if its lack of oil pressure/flow that has caused the engine to start making odd noises, and no one will know until someone competent strips the thing enough to make a reasonable judgement.

If the oil has stopped flowing then its entirely possible that a used complete engine may prove to be the cheapest option, but some initial dismantling first to determine what has happened and why, then a fair judgement can be arrived at how to proceed before the costs of full strip down, only to confirm engine scrap anyway, have to be borne too.

Who you go to i couldn't say, as the car is only just out of warranty maybe there some goodwill offer to be gained by going back to the selling garage assuming it was the Ford dealer, much will depend on service history for this course of action, if it's been serviced on time especailly by the maker's dealer then goodwill will be likely more forthcoming, if its missed services or the present mechanic has started dismantling then that's going to muddy the waters.