You can declare that you are still alive and therefore entitled to continue receiving your pension from a Greek public insurance institution, by booking an online appointment onmyConsulLive so as to be served by a specialised employee of the Consulate of the Ministry of Foreign Affairs.
You will need your personal Taxisnet credentials.
The consulate you need to contact depends on the state where you have your last residence.
The consulate will then send the certificate to your insurance organisation.
Currently, the service is provided for the consulates of New York, Toronto and London. Gradually, more consular authorities will be covered by the service.