Sagging Mattress and poor after-sale treatment

I purchased a Sealy Queen bed at house n Home in welkom, December 2022. Upon delivery I noticed the one side of the mattress was sagging. I delayed my complaint thinking I'm paranoid, but I should have acted then. I then finally complained, and they authorised to change the base; even though I strictly emphasised that the mattress is the problem, they should have sent a technician to physically inspect rather than to rely on mere photos. I had to pay a warranty fee and guess what? Even after changing the base the mattress was still sagging as I specifically told them. Now I'm expected to pay another warranty fee whereas they are the ones who got the inspection wrong. I feel cheated, I'm totally unhappy and won't purchase their beds again. Expensive for nothing, I wasted R8500.