I say again, "The term 'lost sell' is an intentional illusion put forth by lazy sells people". A sell is a discrete event. Before it happens it doesn't exist. Once it happens it can't unhappen (i.e. can't be lost) therefore there is no such thing as a lost sell. You might lose an
opportunity to make a sell. You might have to make a refund if the buyer is unsatisfied but even that is not a "lost sell". The sell was made & your merchandise policy required you to refund the money. You didn't lose the sell. That event occured already in the past & without a time machine you can not undo it. Maybe not even with a time machine.
You can not lose something that you do not have!!!