Mattress Firm review: Tempurpedic mattress and sales person not telling us all the information

We bought a mattress a month ago, Top of line medium Temperpedic $5k mattress. Sales person said she could check the outlet to find if we could get it cheaper. She was so excited, told us we won the lottery of mattresses by being able to get a discount. After a month the mattress is too hard, way too hard and my back ache and shoulder aches are extreme to where it is difficult to get up and I am not sleeping. Went back to the store to see the sales person (S Kingstown RI store) and was told because it was bought at the outlet there was no returns. We were not told this straight out, ever in the sales process. Why would we do this if we are not sure the mattress is right for us. And obviously someone else returned this mattress and had the same issue, it wasn't good. I am extremely upset that I spent $4000 on a mattress that I can't sleep on and I can't return it. I am blind in one eye and was told to sign for the mattress. Again never told I can't return this after trying it out. I will elevate this complaint if I can't get resolution. I just want and need a softer mattress. The sales person I am sure received a nice commission on selling the most expensive mattress and now she will not help. Again was not told that this was not returnable. I am not going to just absorb a $4000 lost without exploring every option to get this rectified.