A customer wants to return the item he bought and wants a refund.

Answer

If the item is not defective and the customer wants a refund, then the seller is not obliged to accept the item and give a refund. Nevertheless, cancelling the sale and giving him a refund is meritorious. There is much thawaab (reward) for giving a refund of the full amount even if the customer has no valid reason for asking for a refund. However, if the seller agrees to take back the item, then it will be a new sale. In this scenario the owner (i.e. the one who had bought the article) is selling it to the previous owner. A new price may be agreed on.