HELP! 96 VW Jetta GLS transmission issues!?

Okay so Id appreciate any help on this, We replaced the transmission only about a month ago. It started with very rough shifting then turned into very iratic shifting, took it back to the shop who did the work. They ran diag and said its elecrtical. SO we replaced the TCM, which took away the iratic shifting but only for about a week. We tried several other TCM's in the car with no luck. Now its lost third gear and overdrive. We took it to another shop to be run with the VAGCOM scanner and NO CODES in the ECM or TCM. The shop has drained the fluid and still no luck. ANY IDEA"S?????