The problem
The showroom sells it. The warehouse finds out later.
Two buildings, one stock figure, and a sale that is agreed in one place and fulfilled in the other. Every gap between the two is a customer waiting for a lorry that is not coming.
SaturdayA contractor picks a tile off the board and asks for sixty boxes. The showroom says yes, based on a figure that was last accurate on Wednesday.
MondayThe warehouse has fifty-four. Nobody tells the showroom, because the showroom is not who they talk to.
TuesdayThe lorry goes out with fifty-four boxes. The paperwork says sixty, because that is what the order said.
WednesdayThe site rejects two boxes as damaged. A note is written on the delivery copy that comes back in the cab.
Month endThe invoice, the delivery and the stock figure disagree by eight boxes, and the contractor is withholding payment on the whole order until somebody explains.
What it actually costsA withheld invoice, over eight boxes nobody can account for
None of this is a pricing problem or a discount problem. It is a document problem: the sale, the issue and the bill were three separate pieces of paper that were never the same document.