Double Payment for Hotel Reservation - Unresolved Refund

I made a reservation through Otelz for Ankara Çankaya Suit Hotel for July 18–20, 2025, and paid ₺5880 by credit card. When I arrived at the hotel, the reception informed me that Otelz had not transferred the payment to them, and that I had to cancel my reservation and pay in cash. As a result, I paid another ₺5880 in cash to the hotel and immediately contacted Otelz. They assured me that the amount I paid would be refunded, but it has now been 25 days and I have received nothing. During this time, I’ve called Otelz customer service multiple times and contacted them via live chat. Each time, I was told they would “follow up with their superiors” and asked to wait. In the most recent call, I was told that the refund process had not even been initiated in their system. I have both the credit card and cash payment receipts for my reservation number 5560909. So far, no solution has been provided. I ended up paying twice—once through the Otelz app and once directly to the hotel—and I’ve been left stuck in the middle. I demand a refund of the excess amount I paid as soon as possible.