Faulty bed within 3months

I bought a bed end of July and the bed is sinking however the store has aknowleged and seen the faulty bed and they are requesting for me to pay for the damage. This damage is bad and they can see it from the pictures that l sent to them. My complaint is based on why l need to now pay 1000r for repairs when l paid 6000r for the bed and l still had to pay for my own delivery fees. I have explained to them that as pregnant as l am this has been very stressful to me and my unborn child and having to sleep uncomfortably is adding to the stress. I have been passed from one person to the other. The regional manager has not bothered to help and the store manager always gives the phone to the sales person who keeps saying they are escalating and its been over two weeks now with no fair resolution. Yes the bed was taken from the floor as it was on sale but l am not expecting to pay 6000r and have a sinking bed and be expected to sleep on it. My baby will be here soon and l can't and l wont be sleeping with my baby on a sinking bed.