Sorry† for clogging up the forum with this message.
On following a tweet, I found a link to http://www.stephenfry.com/store/ where I was offered up a wealth of purchasing options for The Fry Chronicles. I eventually decided to buy the iPhone and audio book versions.
I first clicked the iTunes audio book link, which presented me with the 'enhanced eBook' link for iBooks on my iPhone. I bought this assuming that the enhancement was the unabridged audio. I realise that the audio book is a separate item - the CD available from the Amazon link.
Could you change the link in the audio book column to bring up 'Not yet available' - you might also want to add a link to the lovely ebook that I now own. 
Alex
†As you can tell, I've already read the introduction.
