In the portal, open the shipment and press Raise a claim. Choose Damage, Shortage, Loss or Other, describe what happened, enter the amount claimed (before tax) and add photos or videos.
Claims in the portal lists every claim and its status: Open, Under review, Approved (with the approved amount and credit note), Rejected (with the reason) or Settled. Open a claim to add photos and write to the carrier. The customer is emailed whenever the status changes.