Turkish Airlines Charged Twice for a Single Ticket

I have two Primefly tickets with the reservation number Ue47dh. The only reason I chose Primefly was for the 'free change option' you offered at the time of purchase. I paid a significant extra amount of ₺12,804 in September to get the Primefly tickets for flexibility.

Today, when I wanted to change the tickets, I was told that I need to pay an additional ₺11,072. However, if I try to buy the same ticket from scratch, the price is ₺17,576.

I paid for the Primefly option for free changes, yet you are asking for almost the price of a new ticket on top of that. I always buy Primefly tickets because we need the flexibility, but now I see that this feature is useless and just a ploy to charge us extra. If I had known this earlier, I could have bought Extrafly or Ecofly tickets, as you are asking for a ticket price again when I want to make changes.

We are very loyal THY customers and fly frequently. We buy multiple tickets in advance and always choose Primefly. Unfortunately, I find this very misleading and feel deceived.

I expect you to first explain mathematically why you are trying to charge me twice as much as necessary, as I have outlined above. Then, I expect a refund of the extra amount paid for Primefly. Our trust in Turkish Airlines has been severely shaken. Thank you in advance for your prompt response.