NHTSA Complaint #11601302 — 2018 FORD FUSION

My vehicle has an engine defect from the manufacturer Ford. I was told it is a coolant intrusion from the original design of the head of the vehicle engine. I have had it inspected by Bell ford in AZ however, they will not take responsibility of the defect and saying I am liable for repair. I am confused if it’s a defect in a design from a manufacturer how I am responsible for such said repair the check engine light came on, and I took it in for a diagnosis, no prior issues to the vehicle whatsoever ability wise I’ve contacted customer service and they said there is nothing they can do to contact you guys