If you think, your Seat has a serious defect that affects the safety of the vehicle, report it to the Seat Dealer immediately. If you’re not happy with how the Seat Dealer is dealing with your report, in the UK you should contact the Driver and Vehicle Standards Agency (DVSA).
But before that, you can describe the fault of your Seat in our forum. Maybe some other Seat owner will learn that he experienced the same issue. Multiple occurrences of identical defects mean a better chance of success in a complaint filed with the DVSA. Our website is visited by Seat owners from all over the world.