The Payment Plan Unpaid event triggers after your customer’s payment fails and ALL the auto-charge attempts have also failed. At this point, the payment plan will be moved to an Unpaid/Cancelled status, triggering the Payment Plan Unpaid event actions you have set up.
This event would be used to set up an automation trigger that would cancel any services the customer may have ongoing, and notify your team.
If your customer had not addressed their billing or updated their card prior to the final retry attempt, the unpaid balance can still be paid and the payment plan can resume, if the customer updates their card, or you attempt a manual charge on the current card, from inside of your customer’s Spiffy order record.