There have been a number of reports of unauthorised payments taken from UK banks and via expired cards in the last month or so. The payments show as going to DEH (the Greek electricity company), although it is not clear whether DEH is involved in any way or if it is a third party having access to card & payment details.
In most cases the payment has been refunded by the UK bank in question – after being reported – additionally many of the payments are being investigated by the fraud dept of the bank.
Please be aware that this is happening to some people, and check your bank statements carefully if you use or have used a UK bank account or card to pay your DEH bill.
If you think you have had money taken incorrectly you can report it directly to your bank.
Additionally there is the UK service: https://www.resolver.co.uk/
and you can also report it to the Greek electronic crime dept https://cyberalert.gr/contact/