I Experienced Inconvenience Due To Flight Cancellation of Turkish Airlines

I purchased a round-trip ticket from THY for January 12th SAW-Urfa and January 14th Urfa-SAW. My flight on January 12th was canceled. I utilized my free change right for this ticket and postponed it to January 19th. Later, when I tried to change my return ticket for January 14th through the app, I saw that I had to pay double the normal ticket price. I called the call center and was told they couldn't help but I could leave feedback. I provided feedback. I had such a hard time explaining my situation that each time I received a response as if I had already made the change. Due to the indifference of the authorities during this process and the lack of action to resolve my issue, my ticket was forfeited and I had to purchase a new ticket. I am shocked that I couldn't solve such a simple issue with THY after so much effort. If I, as a Turkish person, have this much difficulty explaining my problem, how do they manage processes as an international company?