Caravan paint and fabric protection

I am about to buy a Bailey Pursuit caravan from new and the dealer is trying to sell me the `Surelook` paint and abric protection - cost £349. Has anyone used this or a similar product? This is not the same as `Bobby Dazzler` or similar after-wash treatment - it`s applied when the vehicle is new and is claimed to maintain showroom condition for at least the guarantee period of 6 years. 

Any comments will be welcomed!