No respect for their warranty, no cover for sales pitch

We bought 2 Lafuma zero gravity outdoor chairs for our pool area from Plaisir Du Jardin in Constantia, Cape Town. Less than 3 years later, still under warranty, the chairs started disintegrating, with one of us literally falling onto the ground when the fabric snapped. We took them in and were told they'd be fixed within about 2 weeks, they'll be in touch. Since we haven't heard, we contacted them again and then we were told the delay was due to some workshop staff leaving or some such. Later when we checked again, the story changed to: "someone tempered with the plastic fabric attachments". When I said there was no way (we're not technical and wouldn't know where to start), they resorted to blaming us for not reading the manual and 'misusing' the chairs. When I said that we bought these for outside and that they were sold to me as OUTDOOR furniture, with no caveats, no special instructions, nothing - in fact, I was promised they are specially made to sustain normal weather conditions in summer (of course they were packed away for winter) - they shrugged their shoulders and refused to repair or replace at their expense. It was our problem, we didn't "respect" the warranty conditions and therefore we're on our own. When we came to collect them they handed them over, ice cold, formal, avoiding eye contact. Gone was the warm, convincing sales pitch of how great these were which is why they were so expensive! We will never buy anything else from them. Expensive, pretty and terrible post sales service with no respect for warranty, their word, or their customers.