In case of hacking, the first thing to do is to change your password and inform users on your site of your hacking. You can also file a complaint with the Gendarmerie Brigade or the Police Office with territorial jurisdiction
https://www.interieur.gouv.fr/Contact/Contacter-une-brigade-de-gendarmerie-ou-un-commissariat-de-policehttps://www.cybermalveillance.gouv.fr/nos-articles/defiguration-de-site-internet/.