Horrible Simmons and Dial a Bed response

In May 2021 we bought a new Simmons Winchester firm bed and matress at Dial a Bed Montana. We were told by the sales lady that this is the replacement of the Simmons Beutyrest Ultra Firm that we bought 12 years ago(which was a perfect bed)The Winchester can carry 150kg max. Nor me or my husband is close to 150kg yet we both sleep right through the matress and both of us is starting to experience back and shoulder problems. We contacted Dial a Bed that send a man out with a max weight 70kg. He sat on the side of the bed(I have the camera footage) After 2weeks I phoned Simmons because they did not get back to us. They said that the man(that sat on the side of the bed) could not find anything wrong with it. This is a R 30 000 bed!!!! How can they not take this problem serious? I even send in the warrenty form(that need to be post in this day and age) this I done the day after purchase(I have a copy)