Is this mechanic ripping me off

My jeeps been to 3 mechanics now got a new tranny and transfer case and still not fixed. The first guy put in a nea tranafer case not even diagnosing the problem then when done error codes came up off

-p161 B communication lost with pcm

-obd11. Because the first mechanic was so eager to keep changing things he dodnt know would fix it i took to another guy that took my money no repairs done and now his boss at a credible shop told us a tranny change would for sure fix it and $3000 later still not fixed and nothing new. Now hes saying it needs a pcm which is what i told him before the tranny change. I dont know what to think anymore ive wasted way to much money and 3 months on this i need some help please any mechanics that actually know what there talking about please give me a little advice.