Turkish Airlines Flexible Ticket Change Issue

I purchased a flexible ticket from Turkish Airlines by paying approximately ₺9000 extra. Due to an urgent matter, I needed to move my flight date earlier. On August 22, I requested through the Turkish Airlines Elite call center to change my flight date to August 23. Despite 13 hours passing and calling the call center about 8 times, my change request was always met with 'we are waiting for approval,' and a new record was created each time. As a result, after waiting for 13 hours and needing to fly on August 23, I couldn't wait any longer since they couldn't guarantee the change, so I requested a refund for my ticket. I am being sarcastic when I say this is superb customer satisfaction. They refunded ₺28,000 out of the ₺31,000 I paid for the flexible ticket. Thus, ₺3000 was unfairly taken from me. How is this customer satisfaction? If you look into it, I was a loyal customer of Turkish Airlines, but now I am turning into a customer who criticizes a brand that has wronged me. I hope Turkish Airlines does the right thing and refunds the unfair deduction they made, especially since they have already caused me inconvenience.