Hi, Tsh.
All payments are handled by WooCommerce and its extensions.
Event Tickets Plus in essence creates products, adds them to the WooCommerce cart (e.g. buy ticket from event single page), and sends emails once the WooCommerce order changes to one of the assigned statuses.
Therefore, please consult your WooCommerce or payment gateway or possibly another extension for this issue.
Please let me know if you have any follow-up questions on this topic after seeking support there.
Thank you.