Unhappy with Rock hard bed delivered

I bought an expensive R15k bed from matress warehouse beginning of the month. Before buying the bed I did alot of research and visiting different bed suppliers to find the right bed. I bought the bed from matress warehouse and when we tested all the beds I found a bed that I was happy with after testing it ect. The bed was delivered but is is rock hard and not the same as the bed we lay on and tested. I was told about the exchange policy but now I get told I must pay an extra R1300 to exchange and get the right bed I want. This is wrong and very unfair that I must pay extra to get the bed I wanted and tested. If I knew this was going to happen I would of bought a bed somewhere else. I am not happy and regret buying this bed from matress warehouse