Malfunction in Turkish Airlines' Online Ticket System Costed Me ₺20,000

The THY online ticket system trick cost me over ₺20,000. I marked the round-trip option on the online ticket purchase page and first selected the departure. While selecting the return, the system switched the round-trip button to one-way without my knowledge. This system glitch happens frequently if you don't pay attention. I called multiple times but received no help. They kept me on the phone for hours, pressing 1, pressing 5, and so on. Finally, I explained the situation and they asked me to send documents, which I did. They said they would call me back but never did. As a result, I ended up with a one-way ticket and had to purchase a return ticket separately. They did not fix the issue and were not helpful. They said they opened a case, but no one contacted me. I called THY and sent all kinds of documents, even recorded a video showing how the system switched from round-trip to one-way. They said they would call, but no one did. I went to the THY airport office, and they told me to call customer service. I will avoid flying with THY both domestically and internationally unless absolutely necessary. Goodbye THY.