Turkish Airlines Fails to Process Ticket Change Request Amid Health Issue

I requested a ticket change from Turkish Airlines due to a health issue and was told I could use it as a travel voucher. I called customer service to create new tickets for my wife and myself, but they failed to create one for my son. Every time I tried to pay, the transaction was canceled. I was transferred to different representatives or told to call back every half hour, which continued from yesterday at 14:00 until 03:00 in the morning. I got no resolution. The price for my son's ticket has also increased since my initial request. Over 15 customer service representatives gave different answers. Two suggested I go to the sales office, but I spoke to them after 02:00. Others said it's unrelated. They can check the calls. I've been and continue to be victimized. My wife and I were booked on the same flight, but not my son, and the price is increasing despite no fault of mine. I demand resolution to my distress.