Sunexpress Lost Luggage on My Germany Flight

I came to Adana with a direct flight from Dusseldorf, departing from Sunexpress on 22 July 2024 at 20:50. We arrived in Adana around 3 am on July 23. Five minutes passed while I was waiting for the suitcase and it still didn't arrive and no one showed any interest. We contacted the lost property office and Havaş officials and they said that the luggage of the plane was empty. All the plane's luggage was forgotten in Düsseldorf and was not loaded onto the plane. It's like a joke. We applied for it to be shipped, but such irresponsibility is impossible. They gave us a number to call, but no one answered. We are waiting, please help, many people, including me, do not have luggage. There must be a solution to this issue. If there is no news for a week, I will take legal action.