Turkish Airlines Refund Issue for Canceled Flight

I purchased tickets for a family of three from Turkish Airlines for a Konya-Istanbul round trip (departure on January 18, 2024, and return on January 30, 2024). Our flight scheduled for 9:50 AM on January 18 was canceled at 4:18 AM, which we only discovered when we woke up to head to the airport. Since we had no connecting flight from Istanbul, we contacted Turkish Airlines for assistance, but they only offered a refund or a change. We managed to get to Istanbul Airport using our own car. Before boarding our international flight, I called Turkish Airlines customer service to request a refund for the canceled departure flight, stating that I did not want to cancel the return flight. Initially, my request was denied. Later, I was told I could request a refund for the departure flight after completing the return flight.
As the return flight approached and I tried to check-in online while abroad, the system only showed options for a refund or a change, not check-in. To avoid further inconvenience for my family, I opted to change the flight to the same one as our original ticket and confirmed the change, effectively checking in. However, during this process, I unknowingly waived my rights to a refund for the canceled departure flight. After completing the flight, I called for a refund and was informed of this waiver and that no refund would be issued.
I submitted feedback on the Turkish Airlines website and attached the email they sent me. Besides the financial and emotional distress we experienced due to the canceled flight, they also charged us for tickets we did not use. I urge Turkish Airlines to address the issue and compensate for the inconvenience instead of adhering strictly to formalities and causing further distress.