Bad customer service and a bad or a reject product

I bought a sealy Tahiti double bed online on the 16 January 2025. The bed was delivered at the end of January or beginning of February. I noticed that by the side am sleeping at is not the same when are sitting on the bed and the mattress is like is being squeezed but on the other side its just fine as if the other side is lacking sponge. On the 12 February I logged a query using their Whatsapp. When I explained to the available agent my problem she said that there is nothing that can be done when I am feeling uncomfortable on the bed and I told her I bought the bed because I wanted comfortability not buying the name. I know sealy beds are comfortable and they last because the bed I had before this one is still in a good condition. I was given a reference and told that I will get a call. After 3 weeks of waiting I did get a call and I was asked to take a picture of the mattress and I did. After a week or 2 I received a call from a sealy agent saying they are not seeing any problem with the mattress and I told her how are you going to see it because you must sit and sleep on it to know that there is problem. She said I must go to the shop and ask there maybe I will be assisted. I did go to a near by Russell furniture shop and I was told that I must log a complain and ask for the exchange but I must do that online. I then decided to call this time around it was on the 17 April 2025 and I was given another reference and that I must expect a call till then I did not receive any call. So today I decided to log on a query again and I was told that my query was closed or the ticket for my query was closed on the 17 April and I was told that the supplier saw nothing wrong with the mattress so there is nothing they can do. Mind you I did not buy the bed from sealy I bought it from Russell furniture shop. I do not know what else to do because I want is for them to exchange the mattress or give me back my money.