Turkish Airlines Denied My Ticket Change Request

I purchased a ticket from Turkish Airlines for the Istanbul-Sivas flight on November 13 at 09:15 (for my brother's daughter's engagement on November 17). Due to reasons from the wedding hall, the engagement was postponed to November 25. Since I work in a government office, I planned to use my remaining 5 days of annual leave for the Sivas trip. I requested a date change for my Turkish Airlines ticket from November 13 to a later date. During my conversation with customer service, I was informed that my ticket was non-changeable, but there was a possibility of assistance if I provided feedback. The response to my feedback was simply that my ticket was non-changeable. Despite Turkish Airlines operating two daily flights between Istanbul and Sivas, they have caused me financial and emotional distress instead of resolving my issue during this winter period. My request is not for a refund, but for a change to a later date! I demand that the necessary actions be taken to reschedule my flight and resolve my grievance.