If you wish to exchange an item, you have to do the following:
You can return the item to the online store. Remember to include a copy of the invoice, a completed return note and the correct return code, and follow the procedure on how to return (which will appear from the return note). You must return the item to us within 14 days following receipt (see return address below). Your money for the returned items will be refunded once they have been received and processed. If you would like another item, please submit a new order.
By following this link you will find the return form and address.
By following the link you will also find a hyperlink where you can buy a return label.