Hi CHERYL,
Brand shopping is one of the worst ways to choose a mattress and I would also completely avoid Simmons mattresses or any manufacturer that doesn’t disclose the quality of the materials inside their mattress or that uses low quality foams in their mattress (which is the case with Simmons on both counts) and that are likely to soften and develop the same issues you are having with your Dormeo much too quickly.
Before you buy a mattress I would encourage you to read the tutorial post which has all the basic information, steps, and guidelines you will need to make the best possible choices … and know how to avoid the worst ones.
Phoenix