If you have been in a transaction with a seller, you can leave feedback. Keep it brief and factual.
You can also use the 'report a seller' link you can find by using 'Help & contact' top left of your Ebay page.
If it is a seller you have not bought from, then move on, ignore them and find a better seller.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)
