As a seller, you should only release the cryptocurrency to the buyer once you've confirmed that you have received the payment. It should be the last step of your trade.
If you release the crypto before confirming you’ve received a successful payment, you can start a dispute, and our moderators will help sort out the issue. For more information on how to start a dispute, take a look at this article.
If you need any assistance from our Support team, do not hesitate to contact us. Check out this article on How to Contact Support.