Send the confirmed spare-kit contents and received inventory together, then ask for availability of each missing item. A dispatch promise for a kit whose cable is unavailable will not help you plan stores cover.
Price the complete replacement before choosing credit. Include the specified cable and all the fasteners, not a cheaper cable that leaves another compatibility question for maintenance.
And ask whether the partial shipment has a separate charge, if you are still considering it. Two small parcels can make a reasonable-looking spare-kit price rather less reasonable.