Same problem at Argos.
I used to have the exact same problem when working for Argos. Except you could check to see if it was in stock with the terminals by the catalogues. Yet every other day you would ALWAYS get some retard come up to the order desk and go...
Customer: "Excuse me, I just checked your stock and it says your sold out of (insert item here). Could you look in the back for me please to see if you have one left?"
Me: "Sorry Sir / Ma'am, our terminals list everything that is in stock. If the terminal says its out of stock then I'm afraid its out of stock".
Customer: "Could you just go check for me please?"
Me: "No problem, I'll be back soon."
Cue ten minutes of me sitting in the staff break room having a cup of coffee.
Other staff member: "Another moron asking for something thats out of stock?"
Me: "Ayup."
Customers tend to be pretty dumb.