Be sure to reade the point 3. Right of withdrawal in the General conditions in the footer menu before returning any goods: 

You can return your delivery in 2 ways:

1) Use the Shipping Return Portal. You wiil need the original shipping Track&Trace code: 
RETURN

 

   
2) Use the manual procedure by filling out and mailing the return pdf

Please, when invoking withdrawal, take notice of the text of article VI.51,§1 of the Belgian Code of Economic Law:

§1. Unless the trader has offered to collect the goods himself, the consumer shall send back the goods or hand them 
over to the trader or to a person authorised by the trader to receive the goods, without undue delay and in any event 
not later than 14 days from the day on which he has communicated his decision to withdraw from the contract to the trader 
in accordance with article VI.49. The deadline shall be met if the consumer sends back the goods before the period of 14 days 
has expired.

The consumer shall only bear the direct cost of returning the goods unless the trader has agreed to bear them or the trader failed 
to inform the consumer that the consumer has to bear them.