I have the same setup in my Gti, except the track/station buttons don't work (the ones on the left side) Alsp, the side buttons on the right side don't do anything!
If the Dis is in audio mode you can change tracks with the up/down buttons on the right, but that's not how it should be. Have you, or your coding expert, found the correct setup, or is yours like mine.
TonyZ