If you were a TheatreCard Plus member, ticket refund protection was always automatically included in your purchase. You may still see a pop up asking if you would like to add ticket refund protection to your purchase, in which case you should select no, to avoid paying the additional fee.
You can now add annual Ticket Protection as an upgrade to ATG+ for £25.
If you do not have annual Ticket Protection, you can add the ticket refund protection for an additional fee prior to the checkout.