Corendon Airlines system prevented us from using the online check-in, leading to charges at the airport for check-in. How can I request a refund for these charges?

Good morning. We would like to point out that a fee of 10 euros will only be charged at the airport if no online check-in was made with the ECO tariff ticket. All of the information on this is passed on to our passengers by email and when they make their booking, when they select the right ticket tariff and shortly before departure. Please find out more about the different ticket tariffs at
https://www.corendonairlines.com/branded-fares
If you have attempted to check in online and the process is unsuccessful, please contact the company via Twitter or Facebook Direct Message with your PNR number so we can check it.
With best regards