800 bucks down the tubes

Recently Jan.2014 my husband purchased what he were told was a Firm Simmons Mattress...The salesman told my husband that it was a very good mattress for a bad back...which is the reason we got the new mattress. Boy were we wrong . Within 10 days the mattress was already sagging and neither one of us could sleep on this bed. It made both of our backs worse that when we started. We had a replacement person come out and they told us that this is one of the softest mattresses and that they always sag like this. We called the manufacturer and they told us that this is also one of their softest mattress....So why then would the salesman tell us it was a firm mattress..We called Hudson and they said they can't do anything. Their sales people are trained professionals and would not give my husband the wrong info just to sell us the mattress....So I guess my husband must be a liar and he made everything up... So we now have a mattress that we can't sleep on...Very poor customer service....So be very careful if you decide to purchase anything here.