Additional info
I have inquired to the post office and just got a reply from them.
They returned because the address was different. I have made the shipping voucher referring a Shipping label from ebay. I checked my copy and it was correct. I am assuming that there must have been some mistake during delivery. The item might have been in the process of transfer at the French International Post office, so could you inquire them using the tracking number? If the item is still in France, they will deliver it again.
この文の続きです。うまく繋がるようにお願いします。