Many will consider Zavvi "fair game" and that it's perfectly fine to hold them to an obvious error that they made in their original listing (listing PLANET EARTH: THE FUTURE as part of this steelbook set).
Congrats to anyone for winning a disc that was NEVER, I repeat never, part of the U.K. Blu-ray set and neither was it included in the 2007 release 5 BD Standard Edition nor was it included in the 2010 digipack release 5 BDs + 1 DVD Special Edition.
Furthermore, the DVD pictured above is clearly stamped "DISC 5" . . . and is from the DVD collection and so the DVD - or DISC 6 - included in the Special Edition BD set was NOT, I repeat not, PLANET EARTH: THE FUTURE.
The system of freebies is not uncommon and if anyone is interested in reading about the PQ problems associated with the earliest batches of the Special Edition 2010 set, the replacement programme for the 2 faulty discs and the complementary copies of Sir David's FIRST LIFE (a documentary on the origins of life on Earth) sent out to unhappy customers they can check out the relevant thread on BD.com.