Walk Behind Lawn Mowers

my mower has a crack deck which caused the shaft to bend. It was purchased through Lowes and they will not stand behind the product. It must of not been put together properly. I have a nice yard and did not hit anything. It started to vibrate a lot when I was cutting the lawn. A friend looked at it and told me what was the problem. My locate dealers dont want anything to do with it since I did not purchase it through them. To me this mower should after only using 1/2 a season be replaceed or credited to another one.