Approved Vendor Status for ISO Compliance

During my company’s last external ISO QMS audit, I was issued a Major Finding for not having the means nor the method for identifying approved suppliers and the items they are approved to supply when issuing a PO. I was thinking I could use the comments box until I found that the information does not carry over from either Vendor or Item card to the Purchase Order. Anyone have any thoughts or suggestions??!!

Vendor Items is a standard granule in Navision, please see your nsc to purchase this.