Mercedes-Benz Persistent AdBlue Issue: Your Thoughts?

I own a 2017 model Mercedes C200d AMG that I purchased brand new from Mengerler Automotive. Despite regular maintenance at authorized service centers, an AdBlue issue has persisted in the car for the past year. Initially coded as having a 5-liter capacity, the tank actually holds 25 liters, necessitating a software update. Continuous AdBlue sensor errors persist—fixing one sensor leads to another error, and resolving the AdBlue issue results in yet another error. It's unclear whether I purchased a car or a bundle of problems. Even the window opening button is broken, despite my cautious use. Researching online, it seems many others are also grappling with similar issues. How much support does Mercedes provide for this vehicle? What does customer satisfaction mean to Mercedes?