I want to return a shipment, so can I get a refund on the duties and taxes? 

If you no longer want a shipment, it will be considered a rejected import, your shipment must comply with strict rules, for example: 

• Goods are defective or damaged before clearing customs  
• They do not comply with the supplier's terms and conditions of contract
• Claims must be made before the goods are returned or destroyed
• Claims must be made within 12 months of the original entry to the authorities

You will still need to pay duties and taxes to FedEx and process a claim directly with the authorities to reject your shipment.