How to handle the certificate of origin when the factory can

Hello, we are a foreign trade company in Changzhou, Jiangsu Province. Now we want to ask you a question. We have a batch of goods exported to South Korea, and the goods are purchased from factories and then exported to Korea directly. Now we have trouble in handling FTA certificate of origin. When we went to the Commodity Inspection Bureau to apply for the certificate of origin, the staff of the Inspection Bureau told us that our products had not been put on record, Therefore, we were unable to apply for the certificate of origin. Later, when we went to the product filing, the Commodity Inspection Bureau said that because we are a foreign trade company, the factory needs to go to the factory for filing. We told the factory that they could not file the product. How should we apply for the certificate of origin in this case?