Tricky one in can you prove it was screen failure. Have you looked on other forums specific to your car or the web in general to see if there is a history of screen failure, which you can use as extra evidence.
I would speak to Motability and tell them you believe it is screen failure and see what they say and request an assessment of how it was fitted at the factory, which can only be done when the seals are off.
Incidentally what car do you have and is it newish.