Renault Express Warranty Denials and Costly Repairs Frustrate Owner

I'm Furkan Mert Iki***. In 2022, we bought an Express commercial vehicle from Renault Istanbul Demirkollar dealer. Soon after, we noticed the vehicle struggled with hill starts. Later, multiple malfunction warnings popped up, prompting us to check the hill start system, airbags, start-stop function, and exhaust emission system. The vehicle even began cutting off the gas. When we took it to the service, they blamed our driving style, specifically, our use of low-speed and Adblue fuel. Renault's solution center provided some support for particle cleaning. However, less than 3 or 4 months later, the same issue resurfaced. The service center informed us that the catalyst was full and needed replacement, but they claimed it wasn't covered under warranty. They demanded 106,000 Turkish liras for the catalyst replacement. We're exhausted from being held responsible for every problem in a less-than-one-year-old vehicle's system. We deeply regret purchasing this Renault vehicle, and as business owners, it's been a source of embarrassment. Thanks.