02 rodeo 3.0 diesel auto box problems

Hi guys, just asking for some general advice. This is a pretty long story so here it goes. 5 months ago I was driving my rodeo, and with no warning at all, the gearbox blew up! Towed it to the local mechanic (would've taken it to an auto transmission specialist if I knew it was the box). Anyway, its been one drama after another. First thing the mechanic said will just drop out the box and put another one in. So he takes mine out. Completely screwed. He sources another one from a wrecker- also screwed. He tells me he is going to rebuild it. Rebuilds it puts it back in- needs a new tourque converter. That then goes in. When on the hoist. It shifts smoothly, as soon as its put on the ground, it stalls. So when its under any load it stalls.

He then thinks its the solenoids, turns out its not. He then thinks its the auto transmission computer. And that's the problem. Nobody can test it apparently because its not common at all. And he can't source another one. So he sends it yo holden to have them say they can't test it, nor can they get another one in, because the car is uncommomen. (Apparently the 3.0 auto combo in th tf only sold for about a year , and they didn't sell many) and now he's just told me is shutting the doors to his work shop. So I now have absolutely no idea what to do with it. Does anybody have any idea with what could be wrong ? This has been going on for 5 months now that I've been without a car. Any help would be greatly appreciated