I am filing this complaint regarding a defective CYBEX Callisto car seat and the companyas mishandling of my replacement request. The tension door of the car seat has malfunctioned three times while driving, causing the seat to become unsecured and putting my childas safety at significant risk. This malfunction is deeply concerning and could lead to severe consequences. Details of the Incident Component Failure: The tension door of the car seat pops open during use, rendering the seat unsecured. This has occurred three times. Availability for Inspection: The defective car seat is available for inspection upon request. Safety Risk: Each malfunction directly jeopardized my childas safety while driving. Inspection: A certified Child Passenger Safety Technician (CPST) and CYBEX customer service both confirmed that the car seat was installed correctly. CYBEX Customer Service Interaction: When I contacted CYBEX customer service to report the issue, they initially refused to replace the defective seat unless I provided a video of the malfunction. This request was unreasonable, as capturing the incident is nearly impossible due to its random nature and dangerous to attempt while driving. After further discussion, CYBEX agreed to replace the car seat under the condition that I remove all identifying product information (serial number, manufacturer date, etc.) and submit photos. I complied with their instructions, but I was subsequently informed that the car seat was out of stock in all colors, requiring me to wait for a replacement. When I later noticed that the car seat was back in stock in certain colors, I followed up with CYBEX, only to be told that they had reversed their decision and were now refusing to replace the seat. This decision, after I complied with all of their requests, including removing the productas identifying information, is unacceptable and unprofessional.