Seems like the problem is something other the transmission itself. I doubt 3 tannys would all make the same noise.
I had something similar a few years back with my GTI. A/C would all of the sudden start blowing hot air when set to like 72 but would blow cold air if I turned it all the way down. VW replaced my whole A/C unit twice. The third time the problem surfaced one of the techs found it was an electrical problem with the a/c temp knob. Simple fix but it took them 3 a/c units and thousands of $ to realize it was something easy.