Very frustrating situation, going to blow some steam!

My advice...FWIW...Find a good, reliable, local repair shop to fix everything right. Get a good welder to fix those issues. And then enjoy your rig. Might cost a few grand. But it will be done right. And these problems/frustrations will be solved.

Buying a new trailer does not guarantee that you won't have problems again. other suggestion would be to just give up on RV'ing. Maybe you'll (understandably) not ever be happy with any RV.