Chapter 1. Notification
When the EPO finds that the holder / applicant has lost a right, a notification is sent to him (R112 (1) EPC).
Of course, this notification is not necessary when a decision is taken by the EPO (R112 (1) EPC) since it is also sent to the holder / applicant.
If the EPO behaves in a way that suggests that the loss of rights has not occurred, then there is no actual loss of rights (eg the owner made a late payment on a due date but the EPO accepted all the following deadlines without comment J14 / 94).
Indeed, any different conduct would contravene the principle of good faith governing the procedure before the EPO (J14 / 94).
Chapter 2. Request for decision
The holder / applicant can always ask the EPO to make a decision in due form when a right is lost (R112 (2) EPC).
This request must be made under 2 months from the notification (R112 (2) EPC).
The decision must then be reasoned (contrary to the mere notification of loss of rights) (R111 (1) EPC).
Only this decision is subject to appeal (A106 (1) EPC).