Why do the brands sold in John Lewis Make up have such crap stock levels?

[JackandDiane]

More than once I go into buy something there and there is a pause and... ' oh no we are out of that one' or ' we are waiting for a delivery'

NOW I tried to order something online ( bobbi brown gel eyeliner pen in violet night if you must know - the other one just fell out of the window) and THAT is out of stock again!