COMPANIES MAKING EXCUSES TO CHANGE THE PRODUCT WHICH IS DAMAGED

I bought a bed at Sleepmasters Mafikeng in 2020. The mattress is broken now I went to the shop to complain they told me I am too heavy for the bed but I wasn't told that when I bought the bed. The branch nevertheless lodged a query. The lady from Restonic and asked for pictures. After sending pictures she said they can't exchange the mattress because it is dirty. I then said I will wash it.The lady never responded we were taking on WhatsApp for me both companies Sleepmasters and Restonic wanted just an excuse to not change the mattress.