Paying to fix lock flaw ridiculous!

I heard about the flaw in the locks of some of the Ford cars and discovered my car was one of them. I took my car in for a service and while I was there made a booking to get the locks fixed, which Ford admitted there was a problem with. To my surprise I was told I had to pay for the locks to be fixed! This is a flaw in the design and the vehicle is in warranty I should not be paying for Fords mistakes! This is ridiculous.