The installed cable is present. Our paid additional cable is missing, but the seller's balance shows nothing outstanding. Their messages still promise it with a future shipment.
Send the balance and the message acknowledging the spare together to the order contact. Otherwise accounts will see a completed order while the person answering you keeps making a separate promise.
Can the order contact get that quantity corrected internally? You should not have to settle the same counting argument with each new person who replies.
Corrected balance received, showing one additional cable outstanding. I have asked for separate dispatch or a priced credit proposal; no new supply agreement yet.
At least the shortage is on the same page now. Keep the original cable reference in the supply proposal, so a later substitute does not create a compatibility question.