Please send the goods from EU without any custom documents (invoices). After testing of the goods in 2N you will receive the credit note. The credit note needs to be confirmed by you. Until we have the confirmation, the credit note is not valid.
From non EU country you have to send the goods with the commercial invoice for a real price (price you paid). This commercial invoice will covered the debt. There won´t be issued any credit notes.
The goods for repair or return have to be always sent with the proper documents, otherwise we will charge you an extra costs for administrative.