How do I supplement the chain of evidence when a local delivery POD photo is disputed?

In local delivery, a POD (Proof of Delivery) photo seems simple, but it really tests your attention to detail when a dispute arises. We had a shipment delivered to a customer's warehouse, the driver took a photo, but the customer later claimed they didn't receive it. The photo only showed the boxes, with no address plate or surrounding landmarks, and dispatch couldn't clarify which dock it was…