I won an item that had a very large postage cost for a small item. In the listing description the seller said they would refund the difference if postage was cheaper than what was charged. This was the reason I bought it as I knew the postage would not be what was charged. The sellers postage price was £10.99 using 2nd class signed for (this was the only option) I checked with royal mail and the postage would be £5.99 so I bought it expecting a £5 refund on postage. The seller has now told me that he sent the item 1st class signed for which is £10 and won't give a refund. I never asked for it to be sent 1st class, 1st class wasn't even an option on the listing. Am I right in still asking for the £5 back as he sent the item using a different delivery method than advertised? Or do I just move on as I paid what it cost to send even though it was sent 1st class instead of 2nd?