Audi TT Chorus grundig radio code needed please.

Hi All
just bought an 03 plate Audi TT, changed the battery now need the code.
theres nothing in the handbook
and Audi want £50 to decode it!

the serial is AUZ2Z2B1381503
GRO Chorus 4B0 035 152 C

thanks in advance
cheers.

all sorted
paid a fiver on ebay for the unlock.