Hi Michael1973,
I would definitely talk with the retailer where you purchased it first before deciding on what to do next.
If you do decide to look for a new mattress I would read the tutorial post here first so you can avoid buying a mattress that may be even worse and develop the same issues even faster (depending on the quality of the materials inside it). If you let me know your city or zip code I’d also be happy to let you know of any of the better options I’m aware of in your area.
Post #4 here has some suggestions that may help on a partial or temporary basis for a mattress that has soft spots or is sagging but if it’s the mattress itself (not the foundation) then there is little that can be done outside of the suggestions there or replacing the mattress with a warranty exchange or a new purchase.
Phoenix