New Opel Astra Transmission Fails at 43k km After Previous Replacement! (Warranty Denied)

Hello. It's disheartening to see internationally renowned brands fall apart one by one. Unfortunately, this time it's Opel, a brand I've used three different vehicles of... My Opel 2020 model 1.5 diesel 122 hp with plenty of gears had its transmission completely replaced under warranty at just 9,000 km while still with its first owner. When I bought the car from its first owner, approximately a year after the first transmission replacement, I faced issues again at around 43,000 km. The dealership suggested taking it to an independent transmission specialist since the warranty had expired. Despite reaching out to Opel GM, they turned a blind eye, suggesting the problem could be due to external maintenance, not even considering examining it. Opel/Citroen/Peugeot group, unfortunately, lost my trust.