This article is from the VW Technical FAQ, by with numerous contributions by Jan Vandenbrande others.
A: The only sure way is to contact the dealer, but you may end up
paying close to 100$ for either the code or a recode.
Some suggest freezing the radio overnight which will reset the
code to 0000, though it may also kill the LCD display.
Hold on that code in a very safe place!
 
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