Unauthorised charge to an ex client after 2,5 years

You keep contacting me AND CHARGING ME for an invoice of 650 Euros which is from June 2024. I have not lived in Belgium since October 2021 and the house for which the invoice has been made for was sold to someone else in January 2022 (I sent you the proof of moving and screenshot of your confirmation email from February 2022 multiple times) . My contract with you has been long cancelled. I have filled the form for this in February 2022. This is clearly not my invoice. Please stop trying to charge me. You are not legally authorised to charge me via domiciliëring as I am not your client. I have contacted my bank, and reported you to the Energy Ombudsman, and the European Consumer Centre.