Mattress Forum

I purchased a Sealys Posturpedic Mattress (and box spring) from Costco less than a year ago and i am unhappy with it. It is slumping in the middle, however, I just realized that my bed frame may not be adaquate enough. My father gave me an old steel frame that does not have a center support bar. I am convinced this has something to do with why I am so unhappy with the mattress. It is a comfortable bed with memory foam on top (i think).

Now I have the option of returning it for a full refund at Costco. I also went to Select Comfort and checked out the queen size mattress there and also have a $1000 coupon off their P6 bed (3" breathable laytex top). Grand total $1500 + $60 (delivery) + $80 (feet for the foundation) + tax of course... can finance at 0% for 6 months and also payoff $600 from the Costco refund. 

I have a few questions:
1) Is my bed perminantly damaged? If not, would it be worth it to get a new steel frame?

2) If it is perminantly damaged, is it worth it to upgrade to the select comfort given my circumstances? (note: i have slept on a select comfort twin mattress for over 7 years when I was growing up; I do like them)

I just don't want to dish out the cash if I don't have to; though this may be a deal I shouldn't pass up.

Thanks!