Parcels missing

Hi There, Our parcels of 12 boxes went missing at customs at the airport in Liberia. Reference number 1ZA6R***. UPS Liberia phoned us and we send our driver to fetch the waybill. He signed for the waybill and when our clearing agent went to the airport customs they confirmed the boxes were delivered and signed by our driver. The driver only signed for the waybill and did not received the 12 boxes. I will appreciate if you can investigate and send proof of who collected these boxes, and not just rely on the signature to receive the waybill.