If you use the return label included in the package, then there will be a 9,95 € return fee, regardless of the value, the number of items, and whether or not any items were kept.
For purchases on invoice, you pay this amount yourself, directly on the original AfterPay invoice. (Tip: If you use the fucntion for registering returns in MyAfterPay, then the 9,95 € is added automatically and the updated amount is calculated immediately.) For other payment methods, the 9,95 € is automatically deducted from the refund.