How can I purchase a headboard for my Artisan base after 3 years?

I bought a mattress and bed from you in May 2013. I am now considering buying a headboard from yourselves but I am unsure from the information on the website which headboards I can choose from.
My order was: Artisan Bespoke - Kingsize (Sprung Edge - 4 Side Draws).
1) What does "Outlet" mean? I notice there are headboards in this section but don't understand the significance of the word "Outlet" on the end of each name. This is the only place on the website I can find reference to buying an individual headboard but the "Outlet" copy makes me think there is something unusual about these particular headboards.
2) I noticed that a list of available headboards is shown in you go in to the "Mattresses" section and go to the Artisan Bespoke but I wonder if somehow the design has changed since 2013 and so I am limited as to what I can choose from.
Please can you confirm exactly which headboards/colours I can choose from and how I can go ahead with a purchase (whether it can be done on the website or whether I should call the office to place the order).
Many thanks in advance!