Bad news my friend, however. Speak to consumer direct and explain what has happened, even though the vehicle is out of warrenty you can still get SEAT to cover this. There is a part in law that states a product must be fit for purpose and function for an appropriate amount of time for said product.
A car which is three years old and only covered 35k miles with full service as per recommendations is not appropriate amount of time for it to fail. Consumer direct will more than likely pass you to your local office and they can advise / take up your case with the dealer / SEAT.
Another avenue is if you have purchaed the car through a finance agreement which lists the car, you could reject the car to them due to the failure as it is actually theres until you finish paying. They don't want a dud car so will also take up the fight.
And finally you can try your insurance company for an engine failure, I have in the past sucked a vast amount of water in to the engine and bent three of the conrods and this was covered and the engine replaced.
Hope you get it sorted.