My Brand New Peugeot 408GT Developed a Transmission Fault Within 2 Weeks

I purchased a 2024 model Peugeot 408GT with an automatic transmission. I took delivery of the vehicle on March 15, 2025. Within 1-2 weeks, I encountered an issue where the automatic transmission would spontaneously shift into a mode displaying only 1-2 behaving like a manual transmission. Additionally, I noticed that the F1 paddle shifters on the steering wheel were not functioning. When I took the vehicle to the authorized service center at Haşim Balaban Oto they gave me a fault diagnosis appointment approximately one month later. During the diagnosis, the vehicle remained at the service center for one day, and they verbally informed me that the F1 paddle shifters were not working, suspecting this was the cause of the transmission shifting into the 1-2 mode. Since the replacement parts for the F1 paddle shifters had to be sourced from abroad, I had to wait approximately 2 to 2.5 months. During this period, I continued to use the vehicle in this condition. On July 21, 2025, the F1 paddle shifters were replaced. I picked up the vehicle from the service center in the late afternoon and experienced no issues on my way home. The F1 paddle shifters were working, and the vehicle was no longer spontaneously shifting from automatic to manual mode; it was functioning properly. However, the next morning(July 22, 2025) when I got into the vehicle and started driving, it began shifting into the manual or “1-2-3” single-gear display mode again, and the newly replaced F1 paddle shifters were once again not working. I immediately took the vehicle back to the service center, where it has been for a week. On the same day, I filed a complaint with Peugeot Turkey. I stated that due to this unresolvable issue, the vehicle qualifies as a defective product, as a brand-new car developed a fault within two weeks, and the service center has been unable to fix it. I also mentioned that they claimed no such issue had been encountered with this model before. I argued that the vehicle is a result of faulty manufacturing and requested a replacement. The customer service representative responded with generic statements like, Peugeot stands behind its brand,sir. If Peugeot(Stellantis) truly stands behind its brand, they should assist with the replacement of the vehicle. The authorized service center (dealership) refuses to even consider a replacement, stating that they can only assist with repairs.