I Experienced Inconvenience Due To Flight Cancellation of Turkish Airlines

I had a flight with Turkish Airlines on November 11th from Izmir to Ordu Giresun Airport with a layover at Sabiha Gokcen, and a return flight on November 15th. My family of four planned to visit our hometown during the mid-term break.

However, Turkish Airlines informed us that the SAW-Ordu Giresun flight was canceled due to operational reasons, citing runway maintenance at Ordu Giresun from November 1st to 12th. I requested to reschedule my return flight as well if I had to move my departure to a later date. They told me that I would need to pay extra to change my return flight since it was booked for a different date.

I don't understand why I can't change my return flight when Turkish Airlines canceled my flight and both my tickets are with Turkish Airlines. How am I supposed to use the return flight if I can't even depart? Despite being a loyal and elite passenger with Turkish Airlines for years, it's disappointing to hear that no one can do anything about this situation.

If Turkish Airlines won't address the inconvenience caused by their issue, why do we pay higher ticket prices to fly with them?