Volkswagen India - Poor service and unresolved engine issues after repair at Volkswagen Arcot Road

I own a **** Volkswagen Polo *.* TDI (third owner). For over a year, the car had smoke near the *nd injector and mild white smoke during cold starts. In July ****, I gave the car to Volkswagen Arcot Road Service Centre in Chennai for oil seal replacement. They diagnosed the issue as a faulty valve door assembly or cylinder head and replaced it along with the vacuum pump and fuel pressure switch, costing ₹**,***.

Upon delivery, I noticed:

White smoke still present.
Fuel mileage dropped drastically to * kmpl (previously **–** kmpl).
Diesel leakage near *rd and *th injectors.
During an injector test, removing the *nd injector coupler did not affect engine operation, indicating a fault.
Despite emailing Volkswagen India, I received no response. The car is not in the same condition as before the service, and I feel mentally stressed and financially burdened due to poor workmanship and unresolved issues.
Attached showing white smoke and diesel leakage.
Screenshot of fuel mileage readings.
Invoice or job card from VW service.
Screenshot of your email to Volkswagen India.