2005 dodge ram 2500 5.9L

There's some weird stuff happening - all of our issues point directly to the ECM (or so 3 diesel mechanics tell me) so I took it to get rebuilt.

A week later I got it back and the truck started right up - WOO HOO. BUT then 6 codes popped up and a knocking started in my engine that was never there before. I took the thing back and told them they must have flashed it wrong to which they told me that it is failing all of their tests still and they would prob have to get me a whole new unit which I was fine with.

So I wait and wait and finally 2 weeks later I come back and it turns out they are giving me my original ECM back and said they figured out it was a quick fix and didn't need to be completely replaced. Took it home and the truck will crank but wont start and now is reading "No communication bus".

Are these people screwing me or is it possible that there is a wiring issue causing this BS?