THTurkish Airlines Ticket Issue for Family Trip

I am raising a complaint against THY. On 03.08.2023, I realized that the ticket I had purchased for my wife and children for the date 13.08.2023 was incorrect. I immediately called for a ticket change 4 hours before the flight. The THY call center told me they could put the ticket on standby, and I had to accept it. Since there were no available seats on the 13.08.2023 flight, the tickets were put on standby for the 14.08 flight, but I saw that there were no available seats on any of these flights. Constantly waiting for flights and traveling back and forth to the airport with my small children was exhausting. I noticed that there was availability on the 17.08.2023 flight at 08:30 and called the THY call center to transfer my standby tickets to this flight, stating that I would pay any difference if necessary. They told me I needed to fill out a feedback form for this, which I did. However, by the time I received a response to this feedback form, there were no seats left on the plane. I had asked the representative about the possibility of no seats being left and was assured I would get a response within 1-2 hours. They responded 4-5 hours later, and it was negative. By then, there were no flights left on 17.08. The only available option was business class, with a ticket price of ₺8,500. This price is exorbitant for three people.