I won an auction and paid $2 for shipping. The seller sent the card in a package which required $3.90 postage. They had put only $.70 on it so it came with postage due of $3.20. I paid this at the PO to get the card. I sent a picture of my receipt and the envelope which had written on it postage due. The problem is the seller does not believe any of this and doesn't think they owe me anything. This is the first time I have ever had an issue with a seller. Should I leave a negative, just let it go, or report them to ebay? Thanks.