Vivense Refused to Replace My Bed After It Collapsed in Months

I purchased a 90×190 cm bed online from Vivense (Order No: FO7D064851e). About 3–5 months after buying it, a serious collapse appeared in the middle of the mattress and spread toward the edges. I paid ₺8,153.20 for the product, and as far as I know, it has a 2-year warranty. After experiencing this issue, I contacted Vivense customer service, but I was told that the problem was due to user error and no solution was offered. However, I have used the mattress under normal conditions and in the proper way. I request that the product be considered under warranty and replaced. I kindly ask that my grievance be resolved.