Automatic Transmission shudder

Does anyone know how to rebuild a transmission"correctly"?.
I have had 3 rebuilds in the past 30 years and all had issues within 1 week after the rebuild. The latest is my 2000 Chevy Express. I was on vacation in South Dakota and I needed to go up hill and my van wanted to go downhill. I took it to a “reputable” rebuild place. It took all week to fix. I picked it up on my way home from vacation. I get on the highway not 30min into the drive and it has a bad vibration between. 35 and 45 mph. I called them, they said the warranty will hold up anywhere I take it… The shop i took it said I need to contact the warranty group. So I did, they said I need to contact the trans shop so I did. This went on for 3 months nobody ever calling me back and soon not even picking up my calls. I got busy and let it laps for a year, now it is out of warranty and the shudder is getting worse. It is not the torque converter because they rebuilt the transmission and it didn’t do this before that. Do I have to shell out another $2300.00? Does anyone have any information? Sorry for the rant.

This situation cries out for the need of a lawyer. You either need one of those or The Godfather to make the owner of the shop cry bitter tears.