Contact eBay through the chat and request to chat with an agent.  If you purchased an eBay postage label and didnt cancel it, you can request a refund but it will take up to 30 days. EBay told me this when I asked them to cancel a postage label. They said they have to wait for Australia post to advise the label hasn’t been used.

If you didn’t purchase an eBay label, ask why you were charged.