Buying a diary

Why is it so hard to buy a diary?  I know it's Febuary but I've been trying to find one since January.  The shops seem to sell them for about a week each side of Christmas, then it appears the vaporise or self destruct.
Now a 2015 diary isn't any good next year so what do the shops do with the ones they didn't sell?  I mean theres no point in sending them back, the printer isn't going to have a use for them. So why is it so bloody hard to find one.
I actually had to order one online, and even then it'll take four days for the shop to get it.
The most annoying part is I tried to get one before Christams but the shops just said they won't be in till January....