Volkswagen Authorized Service Damaged My Transporter After Major Maintenance

I left my 2018 model Transporter with 240,000 km on it at Acarlar Beykoz for major maintenance. When I handed over my vehicle, the only issue was the engine fault light, which I had identified as an EGR problem. After an extended maintenance period, the vehicle was returned to me, but new problems had developed. Upon receiving the vehicle, I noticed a loud knocking sound from the flywheel when shutting it off, significant oil leakage around the rocker cover, and a much noisier overall operation. My vehicle was not this loud before. When I returned to the service center, they claimed the flywheel issue was unrelated to their work and was simply due to wear and tear, suggesting it was a coincidence that it started after I picked up the car. Regarding the oil leakage, they said the rocker cover needed to be replaced. I then consulted another mechanic, a former Volkswagen engine specialist, about the oil used during maintenance. The invoice showed 0W-30 Shell oil had been used. The mechanic immediately recommended draining this oil and using a thicker one, explaining that for a vehicle with 247,000 km, 0W-30 is too thin and inappropriate. I never expected such inexperience from this service center, nor the lack of interest from their customer representatives. My engine block was covered in oil after their maintenance. Following the oil change, the oil consumption issue stopped, and there’s now significantly less oil buildup in the areas I cleaned. I kindly request that my grievance be resolved. I had previously filed a complaint with customer relations but did not receive a satisfactory response.