Poor quality on the Bently matress.

I purchased a king size Bentley in August 2019 from matress King in Pietermaritzburg. At the time of sale I was given a 1 year guaranty on the bed.The rep raved about the quality of their beds and how the Bently was the best. 10 months later and the mattress has started to sink.I have made numerous calls to get assistance .I managed to get an email address from the store and I sent them the picts ,a copy of my invoice and my complaint on 24 June 2020. Every time I called the branch a lady named Arifa told me that the email was not recieved ..back and forth eventually they acknowledge my email when I call them. 26 June 2020..two weeks later and I still dont have any feedback.she said I have to wait for them(Bravo Group)looks like they are waiting for my guarantee to expire..quite *********!