Refund ******

I ordered a tshirt from Spain then I paid shipping and I also paid tax and duties. The t-shirt didn't fit so I returned it to exchange but the company told me they are refunding my money. So I reached out to DHL letting them know that I don't have the item as it was returned and now they refusing to refund my duty fee and tax for the item I don't even have R4236.00. This is a lot of money they are claiming the item was not marked temporary export. How was I to know? Whose supposed to protect the customer in this situation? Must I also follow the route of ******* exportation in fear of being ******.