Turkish Airlines Refused to Refund the Ticket with Incorrect Date Only

First, they should empower their customer service; no one can do anything at this agency. We've been using it corporately since 2020, but the recent incident was a first for me. I mistakenly selected the wrong date while purchasing a ticket and noticed it immediately after payment, but the cancel button wasn't working. I called customer service, and they said no refund is possible. I didn't ask for a refund; I just wanted to change the date or have it open for another day. The amount is close to ₺11,000. Is it easy to earn this money? You just cut it off like that. Whoever plans this company policy, it is absolutely unacceptable. Shame on you for not helping people with their momentary mistakes.