Kia Sorento Rearend problems

I have an 04 Sorento 4x4 and I'm on my 3rd rear axle has anybody else experenced this trouble. I've never had it off road or pulled more than 2000# trailer it has 12000 miles. Thank goodness for waranty.

if I was you I would pay and have a body shop put it on a chassis machine and make sure the frame is no twisted in any way causing problems.