Just bought 2005 A6 with bluetooth, nav, etc., but not voice activation option. Heard that it was installed in all, but not activated unless you purchased option. How do I get it activated, or can I retrofit something to make it work. It has the button on steering wheel, says "not active button" and is on setup screen but can't access. Dealer didn't know what the feature was, could do, or much else about it. Any help much appreciated.