2000 Isuzu Trooper 2000 Trooper trans slippin

I bought my trooper nearly 3 years ago. A few weeks after I bought it the trans went out. I took it to a dealership they said it had fluid and don't know why it was slipping like crazy. I took it to another shop and they said it had no fluid. They rebuilt the trans and it ran again then a month later it was slipping that happened every month for 2 1/2 years they said if I replace the filter and gaskets it would stop leaking. Only to find now that it was not leaking there it was leaking where it attaches to the motor or whatever it attaches to. They also told me all this time that it wasn't leaking then it was. So I just let it go. One day it decided not to go up hills anymore. So I took it to a different shop the next day they filled the trans with fluid only to find it needed barly any fluid at all. I took it the first shop again and they said there was no fluid. They are getting fishy now. And they say the trans is shot. It is just slipping like crazy. What do I do?