Extracting code from my Audi Concert before selling it

I have a single din Audi Concert removed from my A3 2003, works perfectly which I plan on selling due to to upgrading to a double din headunit.

But the code from inside my operating instructions but it appears the serial number on the unit is different to the one in my manual.

Is there anyway I can extract the correct code from the unit using VAG-COM? (I have a proper lead)