Also, the floor sample could be quite old. There is a date of manufacture on the white law label in the back of the mattress. When Tracy says "anything is possible", that goes for the factory, on occasion, mislabeling a mattress before they send it out. It happens....thankfully, not often.

Anything is possible. First check the law tag on your mattress. If the model numbers match then you have the right one. Memory foam in general has a firmer feel to it at first. So it could just be as simple as breaking it in. After a week or two it should be broken in and feel like the one on the showroom floor.

This is actually not that uncommon. There is memory foam in your mattress, it's the material above the springs, and most major brands use a low density, low quality foam, mostly because it's inexpensive to produce and hence, they get more profit. But the issue with the foam is that from batch to batch, there is usually differences in the feel, and that is likely what you are experiencing. Foam is subject to the atmosphere and it can affect the feel and the veracity. Not all foams are going to feel exactly the same. The good news is if you put your foot down and make enough noise about your disappointment, you will usually get the retailer to do something about it. In my store if I have something like this, I will usually offer the customer a topper or some solution before having to do a refund. A topper usually solves the issue. Check out my toppers at www.NestBedding.com

I can’t help but wonder if the mattress you tried at the store was two-sided meaning manufacturers sometimes offer in store mattresses for show that have one side of the bed with firm support and the other half plush support. You may have tried a dual mattress and the sku for your purchase was entered for a firm rather than a plush. Just a thought. Most stores do offer a 90day comfort warranty if you purchased a bed cover at the store at time of purchase.