Sorry you're having problems. Step 1 is to contact your selling dealer to have the problems evaluated. You could contact Heartland directly, but it sounds like perhaps you have. For a problem like doors not closing and walls shifting, it would be difficult to diagnose over the phone or by email. Someone needs to look.
One thing to keep in mind is that differences in how you level the trailer can cause some twisting. If the door latch doesn't line up to the striker plate depending on how the trailer is leveled, the simplest fix is to stop at a hardware store and spend $3 on an elongated striker plate.