Now not taking sides, but what do you want them to say? It is over 4 years old, they don't know how it has been loaded, or where it has been towed. What vehicle is pulling it, what kind of roads, etc. What do you want them to do, give you a new trailer?
I feel sorry for you, and it should not happen. I would hope the axles give way before the frame, does, at least they can be replaced fairly easily. As for the frame, I doubt Forrest River built it. As stated, it is Lippert, and maybe time to go after them a little more aggressively.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT