Horrible Customer service from Sleepmaster

I bought a Sealy Bed from Sleepmaster in Ferndale on Republic. 3 months using the bed , it started to cave in . I launched a complaint with the store which I understand they launched a complaint with the supplier . The supplier gave credit so that I can replace the bed , the store said I should replace it with the same brand , which I refused .They also gave an impression that the store cannot make that call but Sealy. Sealy is saying it is Sleepmaster that needs to make that call . I find this lack competence and better customer care from Sleepmaster. I did not buy the bed from Sealy , I bought a bed from them .6 months later , nothing moved . If I don't follow up they do not bother .