Few questions comparing you to Dreams.

I've recently purchased a bed from Dreams, I am still in the cooling down period of my finance purchase. I've paid £899 which was one sale from £999 for the mattress Therapur Desire 26, and for the Bed together it comes at £1600. I'm more than willing to pay upfront for a better quality and bargain but how can I test your mattresses and what happens if I'm unhappy with the mattress? Can I exchange it for another one, and is there a guarantee and what does it cover.