If you try to cancel transaction after it’s confirmed, it won’t work—blockchain transactions are irreversible once finalized. If your attempt to cancel transaction failed, you can still seek advice by calling 1-888-636-8190. https://writers.coverfly.com/projects/view/4512bd83-e5f2-49e9-a414-1ebc670aab43/What_happens_if_I_try_to_cancel_transaction_too_late