I have a 2012 Vauxhall Insignia. I noticed dampness in the drivers footwell so I took it to a Vauxhall dealership under warranty. After a long investigation, they came to the conclusion that it was an aftermarket windscreen leaking. This is not covered under warranty and I was charged for investigation work. I tried to explain that the car was sold to me by them with the replacement windscreen. Vauxhall says there is nothing they can do and I will have to pay for replacement or a re-seal. Is there anything I can do to say they are liable? I have owned the car now for two years.