There are hundreds, maybe thousands of 5 year old Foci on sale at any given time.
You bought privately, maybe because it was a bit cheaper than from a dealer, whether franchised or not, so don't have the protection you obviously want. Next time, buy from a dealer, and use finance or a credit card for at least part of the purchase.
Now though,it's a case of buyer-beware, just like so many threads on here telling PF'ers who sold a car and the buyer then comes back with faults.

It sucks, but I don't see why you would think this is Ford's problem or even the garage who has the car now, unless the service history shows this dealership previously maintained it and replaced the injectors in the last year.