Essential Dynamic Bed leads to Chiropracter

I bought a Essential Dynamic Bed from the Bed Shop for just under R8000 and after sleeping on the bed for several weeks i landed up at the Chiropractor. I realised it was the bed after spending a week-end away and having no back problems. I returned to the shop to exchange the bed. But they did not want to refund me the difference in money of the cheaper bed and wanted me to pay for delivery again. Then the owner phoned from Namibia and said I would have to pay for this bed to be recovered so that they could resell it. And now they are doing nothing. I don't know how you can resell a bed that causes someone to go to the Chiropractor. Any mattress company who wishes their customers a decent sleep and a healthy back would have exchanged the mattress immediately. This is the business that you are in A good night sleep and a healthy back or is this of no consequence?This is by far the worst mattress that I have ever slept on and the Bed Shop does not honour their promise of quality and fine workmanship. How do you wish to proceed?