ShipScript has been an eBay Community volunteer since 2003, specializing in HTML, CSS, Scripts, Photos, Active Content, Technical Solutions, and online Seller Tools.
If the seller canceled because the item was out of stock, or similarly unavailable for purchase, the seller will automatically receive a strike on their account, so there is no need to report unless the situation is more complex.
If the seller canceled and refunded by falsely claiming that the buyer requested, or something similarly untruthful, you can report the seller here:
https://www.ebay.com/help/action?topicId=4850
