Other Fuel System Pump problems of the 2015 Mazda CX-5

I bought a brand new 2015 Mazda Cx-5 it had less than 50 miles on it. That was December 2015. I gave the car to my son, who has been driving it for the last 2 years. He had the oil changed every 5000 miles with the synthetic oil which I was told was the correct way according to Mazda. On April the 24th 2019 the car died on the highway. My son said the lights on the control panel flashed and the car started slowing down and killed over would not start before it died my son said the engine started knocking really loud. Now the dealership wants 10,304. 00 to fix a car that has a bb value of 12,000 to 15000 dollars. They want to replace the engine,fuel injectors, and the fuel pump and it also blew a fuse that the guy working on it said he had never seen happen before. Now that was a Mazda employee, now I have researched this site and this is not a uncommon problem for Mazda, but the dealership won't own up to it. They just say it is past warranty. I don't need this stress.