Water leak

I have had a water leak since day one with my Fiesta. I bought it from where I work a Ford main dealer brand new. I have booked it in four times at the place where I work twice it was not looked at and the other two times it was sort of looked at. It has taken me 8 months to get it properly looked at to find out it has a faulty welding on the tail gate causing water to come into the spare wheel well. I have had two Ford main dealers look at it with very poor care and the second one saying if you are not happy with our collection and delivery driver bring the car in yourself. My car was thrashed I could tell this by the Ford eco that tells me how the car was driven no fan blades on the gears display now it is going to the body shop for repairs even the tail gate and bumper was damaged with the water testing. Really deep scratches.