Generally speaking, adding a pillow-top is the simplest way to soften up a firm mattress. It sounds like that has not worked so far, though... it could be that the pillow-top itself is not soft enough (thinner pillow-tops are often made of denser foam because they won't last very long, otherwise). Also, memory foam may not be the most ideal material for what you are trying to accomplish; the slow response time means that it is slow to adjust when you move or even just inhale/exhale. Natural latex is a more expensive material, but the quick response time allows it to hold your spine in alignment much more effectively.

The other thing that can potentially change the feel of the mattress is the foundation. For example, if you currently have the mattress on a solid platform, switching to a slatted platform bed would make the mattress feel softer. Sometimes even putting the mattress on a box-spring (instead of the solid foundation most memory foam mattresses go on) can be comfortable. It will take away some of the motion-free properties of the memory foam and make the bed feel more "bouncy," but it will also make it feel softer by allowing more give.

In a word, NO. If they are allowing for restock (which is very weird because they are NOT supposed to do this at all) I would do it.

No what you get is what you get

Hi. I purchased a new mattress from Sleepys because my old one was sagging terribly in the middle. It was around $600 for this Serta memory foam, plus $150 for tax and shipping. I've slept on it for weeks and it's just way too firm, I think it's causing me a lot of bad pressure (around my back and shoulders). I purchased a thin memory foam mattress topper that's 1.5 inch thick, but that hasn't really helped. The store told me if I wanted a different mattress I'd have to pay over $100 for them to come and restock and then pick out a new one (which I'd probably have to pay delivery for again). I just need to soften this a bit so I can sleep longer than 5 hours and not toss and turn. Is there anything I can do to help make this brand new mattress more comfortable?