Awful mattress...

My wife and I were having a hard time finding a mattress that was comfortable for both of us and ended up trying out this mattress while looking for a new bedroom set. We fell in love with the one in the showroom, as it felt both supportive and soft. I wasn't thrilled about dropping 2800 dollars on a mattress, but I figured it would be a good investment if we were both comfortable. The mattress was awesome for about the first month, feeling just like the one in the showroom. Shortly after though it started to sag very bad on both sides and has gotten progressively worse. At this point it is almost unbearable to sleep on. I have to sleep in the middle of the bed to get any kind of support, which is like being back in a full size bed when there are two of you. Also, the box spring makes a loud creaking when you move on the bed. Enough that it wakes the other person up.