Bad beds

We bought a Restonic Dalliance 152 on the 12 March 2017 from House and Home Tygervalley. The bed on both sides collapsed and they replaced in on the 3 June 2017 for another bed, a Restonic Coral 152. They said that the first bed was made for max weight of 90 kilogram. The second bed are classified as a 140 kilogram bed with double springs. We paid the additional monies for the replacement bed and then it happened again, the bed started sagging on the sides again. My wife went back to House and Home and they promised her that they will contact Restonic to contact my wife to solve this problem. My wife also heard from the sales person that apparently this is what happens to all the Restonic mattresses. Needless to say, we are very disappointed and afraid to buy from Restonic again. We just want our money refunded from Restonic so that we can buy another brand of mattress. Kind regards, Hendrik