The Bed Dhop

I've bought a queen bed in 2019 for 4000 but within two weeks it gave me problems and I went to change it, but within six months it started to go flat in the middle,I called the Krugersdorp shop as I've bought it there but they've taken me from pillar to post since then up until now, they want the receipt now of which I can't find it anywhere as I guess I've misplaced it, but I feel is unfair because the bed has 10 years warranty but is less than 10 years but I can't use the bed as it's hurting my back, I'm so disappointed by their service and the people I spoke to they are arrogant,