Turkish Airlines Didn't Resolve My Ticket Issue

In December, I purchased a ticket from Turkish Airlines, and there was a schedule change. Since I had a ticket with insurance, I was entitled to a change or refund. When I tried to change the ticket to a new time that suited me, I was told there were no available tickets. Apparently, because Turkish Airlines flights were transferred to AnadoluJet, the system didn't show availability for changes. However, tickets were visible when attempting to purchase from scratch. I decided to cancel and rebook, but encountered issues during the cancellation process, and the problem wasn't resolved for nearly a month. Since the card I used to purchase the ticket was closed for security reasons, I requested the refund to be transferred to another card. I created a feedback record for this, but they closed my feedback file without resolving my issue. As a result, I am left in a difficult situation and, despite contacting many places, I can't find anyone to address my problem.