It depends upon what you are trying to get from the seller, and whether you need the seller's cooperation or not.
You can get a refund for an item that has not shipped or where tracking does not show delivery by the last estimated delivery date, or a refund for an item that is not as described without the seller's cooperation, for instance.
But you cannot force a seller to accept an offer or to send an item or to explain or reconsider a block or a buyer requirement.
