Pegasus Airlines Lost My Luggage at Istanbul - Cologne Flight

I'm writing to complain about issues I experienced with my Pegasus Airlines flight from Istanbul Sabiha Gokcen Airport to Cologne on June 29. I checked in two pieces of luggage - one blue and one black - both within the weight limit. Upon landing in Cologne, my black suitcase was missing. I immediately reported this to customer service and filed the necessary report.
Customer service informed me that my black suitcase was scheduled to be sent to Cologne on June 30, with no explanation for why it wasn't on my flight. Due to valuable items inside, my daughter offered to pick it up from Sabiha Gokcen. We were told this was possible. She went to the airport at 8:00 PM on June 29 and filled out the required form. However, airport staff then claimed the suitcase had actually been loaded onto a plane to Cologne an hour earlier. We left empty-handed.
When we called customer service again, they contradicted this, saying the suitcase hadn't been loaded and was still scheduled for June 30. We kept receiving conflicting information. On June 30, despite calling every hour, we were told there were no updates and the suitcase couldn't be located. This left us without necessary clothes in Cologne, stuck in rain and mud. Being Sunday, stores in Germany were closed, exacerbating our predicament. I'd also like to note the time and money wasted on airport trips.
I have a return flight on Monday, July 1, but my suitcase is still missing. I've suffered significant material and emotional damage. I demand an immediate resolution and compensation for my hardship. I intend to exercise all my legal rights regarding this matter.
Please address this issue and respond to me as soon as possible.