Sleep on new bed for 3 days , bed broke!!

We brought a new Posturepedic double bed from Sleepmasters Benoni , that is very pricey , when I complained about the bed , they sended a guy from Restonic to come and check the bed , he came 2 days afer the complain . This guy said its our fault the bed is like that , take in concideration only the one side is flat !!! He said we must take a queen size rather it would be better .. I dont want a queen size bed thats why I took a double bed , I do not have space for a queen , who the hell is he to tell me must take the other bed , I want another double bed !!! Same price different bed thats not so useless , and why only sagging the one side , weird, I want a new bed today , I will not pay my debit order without a new bed !!!