Turkish Airlines Overbooking Issue on Flight

I would like to share an incident that happened to me on 12.06.2024 and request a resolution for my grievance. I had a flight at 17:00 on 12.06.2024. I couldn't complete the online check-in due to an error. I arrived at 16:10 and tried to check-in. The staff said the system wouldn't allow it because the flight was full. They mentioned that in cases of overbooking, you might lose your check-in rights if you don't do it before 16:15. The online check-in error and the situation in Istanbul are being exploited, seriously depriving people like me who arrive in the last 10 minutes of their rights. The system wouldn't allow it, and they created chaos by saying the flight was full, telling me at 16:20 that my rights had expired. They gave me a ticket change card and sent me to ticket sales. I explained my situation, and they said they couldn't help. They offered the nearest available seat at 23:55 in business class, asking me to pay for it. I wasn't allowed on my original flight due to overbooking and had to buy the new ticket because I missed my cousin's wedding and needed to get to Izmir. The boarding time for the 23:55 flight was 23:25, but they made the last call at 23:05. This wasn't displayed in the lounge, causing many people to miss the flight. I accidentally saw the chaos at boarding while stepping out for some fresh air and managed to catch the flight. A passenger politely pointed out that the boarding time was listed as 23:25. However, the staff scanning tickets rudely scolded passengers, saying 'hurry up'. I explained the situation to a gentleman claiming to be the supervisor, pointing out the mistake on the screens and the potential for people to be affected. He yelled at me, saying that last call can be made before the boarding time, that he was trained for this, and told me to 'reach his level of education before speaking to him'. This was an unbelievable experience with Turkish Airlines. I purchased two tickets: one for 17:00 on 12.06.2024 and a business class ticket for 23:55 on 12.06.2024. I am requesting a refund. They caused me significant financial and emotional damage, and I ask for appropriate action to be taken.