Your supposed to use the label supplied by eBay where tracking is automatically entered,if you don't do this and use your own postage you may be able to change the tracking here https://www.ebay.co.uk/sh/ord/?filter=status:ALL_ORDERS after you generate the original eBay label.
If the buyer paid for postage they will be refunded within 30-40 days
If you paid then you need to apply for your refund within 14 days of sending
