Issues with Turkish Airlines Flight Cancellation and Refund Process

I purchased a round-trip ticket from THY to Antalya. According to the refund conditions, I was informed that there would be a deduction of ₺525 if I canceled the ticket. Based on this information, I canceled my return flight, accepting the deduction, due to a change in my return date and time and not finding a suitable time with THY. When I wanted to know when the refund would be made, customer service told me that my refund would not be processed because I converted the round-trip ticket to a one-way ticket. At the time of purchase, the one-way ticket price for both departure and return was around ₺1,500. I purchased a round-trip ticket and paid approximately ₺3,000 in total without any price difference. If the refund is not processed, I will have paid ₺3,000 for just the departure. The customer service representative said that if I canceled the round-trip ticket, a refund could be made. So, I decided to cancel the departure as well. However, I learned that if I cancel the departure, the refund will be based only on the departure fee, not the ₺3,000 I paid. I am currently in a difficult situation due to this issue and urgently request a refund for my return flight after deductions. It was specified at the time of ticket purchase that both tickets could be refunded with a ₺525 deduction each. This condition applied to each flight when selecting them. I am feeling greatly inconvenienced by the current situation and expect a resolution from THY.