I am still not buying the FC excuse about the website updates and 10 days as that is total "swear". you COULD NOT book 10 days on the web anyway.
I don't think they mean their website.
I think they mean what is known as the "backend" booking system, the one that their staff and other travel agents use to book.
The website system would also be connected to this, but it is completely feasible that they have never offered those durations via the web for a number of reasons:
They may wish to discourage them in favour of the more starightforward 7 & 14 day durations.
They may consider these bookings to be more specialised and best handled by staff rather than online booking systems.
If this is the case they would probably need to suspend web bookings during this period for fear that the bookings could be lost, or cause database problems if placed whilst the system was being changed.
Needing a week to do this sounds like a long time to do it, but it may be the case that they are actually working with an outside supplier who needs to be booked this far in advance.
Whilst I am no expert in travel systems, my background is in IT and in particular web based systems, and I have been told that some of the systems in the travel industry are particularly archaic and not easy to update etc.
To me at least it does have a ring of truth, yes it might be a fib, but if it is, then it is far more convincing ( to me ) than anything they've fibbed about in the past.