Turkish Airlines Check-in Fee Shock with Economy Class Ticket

I purchased a flight ticket from Turkish Airlines and tried to do an online check-in 12 hours before the flight. However, I couldn't complete the process due to a surname error warning. I called THY customer service for assistance, but they informed me that since my ticket was economy class, the check-in was closed. They said I needed to pay an additional fee to open it and be able to fly. Despite expressing that this was unacceptable and speaking with different representatives multiple times, they all stated that this was a new policy, mentioned in the small print of the sales terms, and that even if I did the check-in at the airport, I would still have to pay the same fee. As a result, I had to pay a ₺850 check-in fee. I noticed on my card statement that the ticket was issued in the name of Kayseri. I am complaining about the individuals and institutions who identified themselves as THY personnel and caused me to incur this fee.