vag com is adapter cable and software to read and change codes via OBD plug. see
www.Ross-Tech.com
What you describe is limp mode
To get transmission out of limp mode:
1. conduct adaptation of Throttle Valve Control Module
2. conduct adaptation of Kick Down Function
3.read DTC codes
4.erase DTC codes
5.regenerate readiness code
1-5 are accomplished with a vag com. Anyone with one should know these procedures.