That is the replacement disc for the original box set (which contained an error) ... email your distributor immediately. If you received the replacement, the company (Nuclear Blast in US it sounds like) assume you have already rec'd the set. I hope it hasn't been lost in the post ... email directly.
You say Burning Shed has been contacted? Have you got the original order number? This is unusual for them not to reply, they are usually prompt?
Try this email address:
With all info you have inlc. order number
Same thing happened to me... Replacement disc arrived before the box set. Contacted Burningshed and they said that it takes six weeks to deliver to where I live...