Turkish Airlines Flight Booking Issue

Before my flight with Turkish Airlines, my ticket was put on hold and I couldn't board the plane. They could only arrange a seat for a flight 8 hours later and offered an open ticket as compensation. I was informed that I could change the date of the open ticket through the call center up to 1 month before the flight date. The call center stated that I could perform this transaction at Istanbul Airport or from sales offices. However, the sales offices do not answer their phones, claiming they are too busy to accept calls. I was told that I need to go to the sales office or the airport to make this change. Thank you for not caring about customer satisfaction. After changing the date of my open ticket, if necessary, I will use a bus, but I will not buy a ticket from Turkish Airlines again.