I suggest you open a case with Ford Corporate, there is a number somewhere, I will see if I can find it, I agree with an earlier post, warranty should cover failures that occur in an unusual time frame. Your slippage may be due to a leaking slave cylinder, or other issue unseen, but with the mileage you have, this is not something common, unless it was prior abuse, but even abused, at that mileage, really? Again, review the warranty information on the Ford website on transmission and clutch and then open a case with corporate and site the dealership that you are trying to work with. Good luck and remember, you get more flies with honey, don't berate the people that will be trying to rectify this. 800-392-3673, also contact the BBB in the area where you bought the car, they will take your complaint and the dealer will want to reply and work with you if it is a reputable dealer. Take notes, keep a timeline, review before talking.
Vhttps://www.fordservicecontent.com/Ford_Content/Catalog/owner_information/2016-Car-Lt-Truck-Warranty-version-3_frdwa_EN-US_10_2015.pdf
Vhttps://www.fordservicecontent.com/Ford_Content/Catalog/owner_information/2016-Car-Lt-Truck-Warranty-version-3_frdwa_EN-US_10_2015.pdf