Mercedes-Benz walks away from standing behind product

I am not sure linkedin will post this but I need to say it. I brought my 2015 C300 into Mercedes-Benz of Naperville Sept.1st for brakes, the morning I brought the car in it was running rough. I told them to look at the brakes and see why the car was running rough. The car has 48,888 miles on it and is in very good condition. We barley drive the car. I received a call from Mercedes of Naperville on Sept. 1st at 6pm. I was told that the reason the car was running rough was I lost compression in cylinder 4 and that the engine needed to be replaced. The cost would be$16,228.!!! I realize the warranty was for 4 years or 40,000 miles but give me a break. There is no question I believe there was a flaw in the engine and have been told this is an ONGOING ISSUE WITH THIS MODEL CAR. Corporate called me today and said they would offer a 10% discount. This just seems unjust. Any thoughts???