Turkish Airlines Call Center Misleads Passengers, Causing Inconvenience

On May 10, 2024, I purchased 3 tickets for myself, my spouse, and my son: Istanbul-Los Angeles (August 18) and Los Angeles-Istanbul (October 4). Since our departure date was fixed but our return date was uncertain, I chose a refundable class for the return ticket. Before completing the transaction, I contacted the call center to confirm if a refund for the return ticket was possible. They confirmed that it was possible before the flight and that the full amount shown would be refunded. Subsequently, I saved screenshots of every step of the transaction. I completed the IST-LAX flight. However, due to the uncertainty of my return date, I attempted to cancel my return ticket through the mobile app. At the final step of the cancellation, I received a nonsensical message stating, "All seats in the selected fare class are full." I contacted the call center again, where the representative informed me that canceling the ticket was not possible, and that I would only be refunded a little over a thousand ₺ per person. I was told that because my outbound ticket was non-refundable, my return ticket could not be canceled either. If the rules of the outbound ticket apply, why was the "fully refundable" option offered when purchasing the return ticket? I paid a significant amount more for this ticket to make it refundable 100 days ago. I am requesting the cancellation of our return tickets and a refund of ₺91,276.92. The rule supposedly dictates that the most restrictive fare rule applies. However, if that is the case, why was I presented with the "fully refundable" option when purchasing the return ticket when I had already chosen a non-refundable fare for the outbound ticket? The option should not have been available for someone who selected a lower class for the outbound ticket. Furthermore, the "fully refundable before the flight" rule should apply to all flights if it is advertised that way. In that case, the terms should clearly state "non-refundable outbound ticket" and "fully refundable before All flights" for the return ticket. Someone who purchases a "fully refundable before the flight" return ticket would expect like I did, that they could cancel a ticket they have not used. Besides, when I spoke with the call center, they confirmed that the full amount would be refunded as shown on the screen. You can listen to the recordings for verification. I urgently request that my refund processed