I've been buying and selling on eBay for 2 years with no problems, until now. Sold a pair of expensive real ugg boots. Sent them 1st class recorded on 21st November, but they haven't arrived. When i do track and trace the royal mail website says that the package is being processed by royal mail. The buyer has opened a case against me and wants refunding by 8th December. What should I do next, other than keep checking whether it has been delivered or not?