My radio in 05 Touareg display only 99 discs, as well as 99 songs per disc and it seems as if it only plays the first 99 discs and first 99 songs per disc.
Q1: Am I correct here?
Q2: Is there perhaps a fix for this?
Since nobody else answered yet, perhaps this will be helpful...
In my BMW, the head unit can only display "track" numbers (which could be disc / artist / track /etc. depending on what mode the Phatbox is in) from 01 to 99. After 99 it displays blanks for 00, then continues with 01, which really means 101. I have over 2500 discs / playlists on that Phatbox and it works fine, once you get used to the display.
A friend's car has a Kenwood head unit and Phatbox that I installed for him. He enters the disc he wants via the digits on the remote control. His head unit won't accept an input > 999, so he can't directly select the last 1500 playlists (same DMS as my BMW) directly - he has to be in artist mode and select the appropriate artist number, then use "disc up" to get to the specific disc he wants.
Some Phatbox head unit firmware is selectable between 99-disc and larger numbers, and should be set to match the head unit's display capabilities.