Mattress One

I've had my mattress for almost six months now and let me first start by saying it's absolutely thee worst mattress I've ever purchase. When I first went to buy the mattress the sales man was really nice and reassured me that if I didn't like it I could trade it out for a different mattress with no problem. But once the mattress was paid for and I got it home all thay changed. I was told that under any circumstances could I trade it in. A total waste of $800 and now I have to by a new mattress after only six months. I also believe that the mattress was previously used before I purchased it.