Good evening Richard and welcome back!
Thank you for reaching out to us.
We are sorry to hear about the tickets acting up on your client’s website. Yikes!
I would love to help you with this topic.
I believe this might be caused by the checkbox Try to set the status of new ticket orders to “complete” automatically under Events -> Settings -> Tickets being overly aggressive.
Try unchecking this to see if it helps.
That being said, in order for the ticket to be sent, the order status still need to be set to “Complete” (manually or otherwise), but not until the actual transaction goes through!
With that in mind, there are a couple of third-party plugins that do offer control on the conditions to set an order to “Complete” automatically.
Additionally, a lot of our users are also happy with: https://docs.woocommerce.com/document/automatically-complete-orders/
Let me know if that helps.
Have a great day!
Geoff B.