I have a 1996 fuso fe-sp, I took it in to a local shop for service and transmission check as it was not shifting up and locking up in reverse. After servicing and the transmission inspection,I was told the transmission was in need of replacement. So the company sourced a rebuild and installed it, that unit failed and the supplier sent out parts to fix the issues, this did not work. So the unit was removed and sent back to the supplier. They renewed it ? And sent it back, same issues! Now they are arguing with the supplier and have now told me the turbo is bad ( stuck open waste gate) and they are claiming this is causing the transmission to not operate properly.
this has been on going for over four months.

any experience or advice?