The problem was a bit of a technical hitch with reprinting new copies (and thank you to every one who bought all the first print run!) but it has all been sorted out now, and shiny new copies are in the shops and on-line. It maybe that a similar delay will happen with one of two of the other titles - if so, don't worry, they will be back.
In the mean time, don't forget you can always go and borrow a copy from your local library (if they don't have a copy, you can ask and they can order it for you.)
I was in my local bookshop, Heffers, in Cambridge to collect some books for a school visit and spotted lots of new reprinted copies of The Phantom Lights along with the rest of the series - and with our lovely bookshelf neighbours, James Nicols' The Apprentice Witch and A Witch Alone (if you haven't read them, you must - they are fantastic!) and an author you may just have heard of called Michael Morpurgo . . .