warranty on spring air matteress

3 yrs ago i purchased a mattress from jc penny, My wife and i have back pains and when we shopped for one we thought i would be a good idea to purchase a good one, so with the help of the sales lady at jcP we brought a spring air with pillow top, since it was such a tall mattress the sales lady told us we could use a 5'' boxspring, so we used the bed and we noticed the center had sunk about 5 inches, i called Spring air who told me to call on JCPenny, so i call they sent a man from the Mattress Marshall co in Md. he came out laid a aluminum tube across the bed with a measurement card and took a picture , told me it was fine, i laid in the bed and it sunk,, he said all he could do is take the pics as directed, we struggled with the mattress to get it off so he could do the same with the boxspring, while the mattress was standing upright i showed him how the bottom was sticking out in the center , he said yes so i asked him to take a picture of that he said all he was told to do is take a pic of the alum rod that laid across the bed..i called the manager of jcPenny and said there was only verbal report because the co somehow lost the pics, so he had another co come out he did the same thing except he used a string across the top of the mattress, he too saw as i laid in and there it sunk 4-5'' he said the same that all they want is a pic of the measurement card,, he said he felt for us, but that was all he could do,, never did hear from him again, i go to the store and they have a sale for 50% off mattress, so i go in look at a different type and was going to purchase it and forget about this whole mess but when they give me a price it was 30% OFF WHAT IS GOING ON IN JCPENNY,,,, please let me know if there is a sue case going on... thanks Joe