Recently relocated and furniture was a must..we opted to ...

Recently relocated and furniture was a must..we opted to visit City Furniture /Ashley's in Naples, Florida. The employees were accommodating and friendly and of course we purchased furniture for every room in our new condo.
Due to the pandemic the delivery was sporadic..we understood that and waited for all the pieces to arrive. What we didn't expect 5 months later was for our mattress to start sinking. We went back to the store and was told we needed to contact the mattress manufacturer,for they were not responsible for any defective items.
We tried every day for a month, to no avail, and finally went back to the store and had them contact them directly. Sure enough..the manufacturer immediately picked up the call and was sending someone to our home for evaluation. Person arrived 4 days later to evaluate and the manufacturer called later that day with the results.
They said there was nothing wrong with our mattress, meanwhile my husband and I are sinking in it. We're not heavy people. We were willing to upgrade provided they would credit what we had purchased..but their response was simply UNFORTUNATELY there's nothing wrong with our mattress. Remember it's only been 5 months and not YEARS.