Turkish Airlines Seat Change Issue

On the morning of July 13, 2024, I purchased a ticket for Turkish Airlines flight TK2658 from Istanbul to SIV. When buying the ticket, I selected my seat and paid for it. However, until the day of the flight, the seat I paid for kept changing. My seat number changed 4-5 times, and I couldn't sit in the seat I had purchased. I had chosen a seat with extra legroom, but I was forced to sit in a regular seat. There is no need to pay for a seat when buying a plane ticket because the company has the right to change it as they wish. This is the explanation given by Turkish Airlines. The seat fee system seems to be designed to extract a bit more money from you. Such behavior is not befitting a company like Turkish Airlines.