You must cover the cost of returning an item yourself if you decide to return an item - even if the original delivery of the item was free.
Shipping fees are the following if you use the attached return label:
Return of a faulty item
If an item you have purchased in our webshop has slipped through our quality control checks with a fault, you are not liable for the cost of return postage when returning a faulty item to us. When returning a faulty item you have to use the return label included in the package and a complete return slip.