David Fouque

Hello I sold a item to a customer in the UK. The customs duty was paid on import. The item then later developed a fault during the warranty period, so the item was returned to us, free of VAT and duties of course. The item was repaired but when we returned the item back to the customer, with a pro-forma invoice declaring the value of the item but with mention that the values were for customs purposes only, the customer was then asked to pay duty for the item.. As far as we are concerned this shouldn't have happened, and we are obviously keen to avoid it happening again, so how do you return a repaired faulty item back to the customer without them being asked to pay duty? (as the duty was already paid upon the original purchase).