frame on couch broke

I purchased a couch from Art Van in 2014. We spend 6 months in Florida and when were in Michigan we spend half the summer at our trailer at the lake.  So my couch gets about 3 or 4 months of use a year. I sat on the couch at Christmas time and there was a loud cracking sound. I called Art Van service department to set up a service call but they couldn't get anyone out before we went to Florida.  When we had them out when we got back from Florida they said the bottom seat rail was broke (twisted out of place) and a board cracked. The couch was rated a 4 in condition. They said it looked like it had just been delivered. The service department wanted over $500.00 to fix it. Because the couch is in such good shape  and used so little needless to say I was unhappy. I called the England customer service number and left several messages but nobody bother to return my calls. I feel I deserve a return call and some compensation on repairs as the couch was defectively built. The cushion never sat flat on the couch they were always tilled which tells me there was a problem when the couch was delivered. When I asked about it I was told they would level out. They never did!!