[kelchm]

The feature isn’t “locked” — it’s just a configuration option on one of the control modules in the car based on the original build configuration. Keep in mind that a specific module might be used on many different models of car.

Why not just have the rear speaker outputs enabled at all times even on vehicles that do t have rear speakers? I suspect it’s as simple as VW not wanting to show the front/rear fader control for a vehicle where it isn’t applicable.

FWIW, this absolutely can be done yourself using VCDS or OBD 11 to update the module settings.

I suspect in this case the dealer wasn’t telling you the entire truth — it may be as simple as them not having an established procedure for this in house and wanting to just get you to go away.