Returns, exchanges, and refunds

What are the conditions for returning an item? How do I make a return? Is the return free? How long do I have to make a return? Can I exchange an item for a different model or color? Can sale or promotional items be returned or exchanged? Can I return an item I received as a gift? How long will it take to receive my refund? How will I be refunded? My refund has not arrived. What should I do? My item has a defect. What should I do?