Bed bought at Bed direct has defective mattress

On Saturday (27 January 2016), I inquired by calling Bed Direct using the number given on the website for their Midrand store and I spoke to Bethuel and I explained to him what I was looking for, i.e. a strong bed that was steady and reliable and could handle the weight of up to 120kg. He recommended a bed that he indicated they often sell to the hospitality industry, assuring me of its durability and reliability. I thus made the decision to buy the bed based on this. The bed was delivered to us on Monday and yesterday the person it was bought for alerted me to the fact that the mattress has sag areas. I then emailed Bed direct and Bethuel tried to convince me that this is how beds are and yet that is not how my bed or my sister's bed is. He said that he would escalate my complaint to their manufacturer, that being Rest Assured and get them to send someone to have a look at what the problem is. If this is how this bed is, I believe that Bethuel misrepresented the quality of the product and led me to believe it was of a quality it was not. Misrepresentation of facts to secure a sale renders a sale contract voidable and it is a material factor. No one has called me about this still