Unfortunately, a retailer is not obligated by EU law to cooperate with VAT refunds. Even though you are in your right by EU law to reclaim the VAT, and a shop merely has to perform a small administrative act, a shop may choose not to be of service.
If a store chooses not to cooperate with refunding your vat via vatfree.com you can file a complaint by contacting their customer service, or through social media. Sometimes stores will make an exception after you have contacted them directly. If a store hears about the disappointment from enough customers, they often choose to change their refund policy.
Please check to see if a store cooperates in our shopping guide, before you send your original receipts to our office in the post. If you have sent us original receipts from an uncooperative store, and it turns out the store does not wish to cooperate, we can not return your receipt to you or forward them to these stores, competitors or other claiming parties.
See also the page 'What to do if a shop does not cooperate'