Issue With Accessing My Turkish Airlines Ticket

I purchased a round-trip ticket from THY with the PNR code VMXBM7 for Istanbul-Sanliurfa. Later, I put the ticket on hold. On August 20, I was informed by a customer representative that I could change my ticket for free until December 9 or get a refund. However, when I called again, I was told I could change it for free until September 31. I reported the situation to THY via feedback but received no response. Since yesterday, I have called customer service 5 times to use the ticket. Each time, I have a 20-25-minute conversation, and they tell me they cannot access the fare rules of my old ticket and will escalate the issue to higher authorities via email and get back to me. I still haven't received a response. This situation is not befitting of THY. I request that my conversation on August 20, 2023, be reviewed, my grievance be resolved, my ticket be changed for free, and I receive a response within a short period.