Turkish Airlines Overcharged Me for a Flexible Ticket Change Despite Errors Online

On March 28, 2024, I purchased a ticket with Turkish Airlines for July 31, 2024 Ankara - Los Angeles departure and September 3, 2024 Chicago - Ankara return, paying ₺41,509. Due to the change and uncertainty of my travel return plan, on August 23, 2024, I changed my ticket to Chicago - Ankara on October 8, 2024 on the same route as a primefly flexible ticket by paying ₺5434. However, when it became clear that I would not be able to return on this date when I wanted to enter the system to make changes again, I encountered the error code in the complaint attachment. I thought it was a system error and sent it to them via feedback. In response, I was informed that I should make my ticket change transactions through the call center without specifying the reason. 3 years ago, I had the problem of changing my ticket on the same track with the same error code, and every time I called the call center, I was informed about different change fees, and finally it was revealed that my ticket could be changed free of charge. Despite this, I reached the call center and was charged an additional fee of around ₺17,000 for the ticket I had booked as flexible. This also included a call center service fee. I stated that I was trying to change my ticket through the call center because it could not be changed online due to an error in the Turkish Airlines system and that I did not want to pay the fee, and that I had booked my ticket as changeable and that this fee was quite high, and unfortunately I hung up the phone without any result. Afterwards, I created feedback again, stating that I had the right to change my ticket online, just like every other airline in the world, and asked them to correct this systemic error. But again, each of my feedbacks was answered in a very unserious manner, far from problem solving. In fact, in the last feedback, I was informed that after making an online ticket change once, I could only make the necessary ticket changes through the call center. I asked them to send me a consumer-oriented statement in this regard, but I was given a frivolous answer that the feedbacks were duly answered and that no different application could be made. What I have requested from the company is to be able to change my ticket by seeing it on the online system and my free change right promised in accordance with the flexible ticket conditions. But they refuse to take the slightest responsibility in this regard.