Is Vauxhall liable for the wiper motor failure on my 2016 Corsa?

My daughter has a 2016 Vauxhall Corsa. She recently had to have the wiper motor and linkage replaced as a single unit. We thought this would be covered under warranty but she ended up having to pay £415 as Vauxhall stated it wasn't covered due to cold conditions causing the wiper to freeze to the screen. She had the autowipe system switched on so when she started the car it saw the frost as rain and tried to wipe the screen. Nothing at all is mentioned in the handbook about turning the system off or not using the wipers if the windscreen is iced up. I have a copy of a letter from Vauxhall to the dealership telling them to expect failures in the cold weather and that the part is therefore not covered. Any ideas of how to challenge this?
Definitely worth making a Small Claim against the supplying dealer. Some people would know that switching on wipers that are iced to the screen would burn the motor out. That's why in countries like Austria and Germany drivers leave their wipers sticking up off the screens. But an ordinary British owner cannot "reasonably" be expected to know. See:
Answered by Honest John on

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