Money removed from the account but transaction was canceled

I need your advice since I had a transaction using revolut card in Greece. Revolut charged me with the amount but the ATM machine showed that the transaction had been canceled. Who can I contact?

If you look at the transaction in your Revolut account does it show as ‘Pending’ or ‘Completed’.
Assuming it’s Pending it is most likely that it will not complete and your balance will be updated in some days time. If it does complete you will need to contact support for a chargeback form.
Keep any slips you have from the atm.