Hi, Customs fees by carriers are a rip of, they collect fees from recipient, no matter if paid by sender. My advice is to always challenge. Since brexit I regularly Organise shipment by my company; large multinational US based corporation. We have a customs account with all major carriers, despite this when delivered in UK, the carrier issues invoice to recipient, when challenged they admit admin error. Imagine how much they make of ones never challenged when they charge 20% vat plus handling charge.
Jim Mackenzie