Volkswagen India — battery died after my service

Address:

Rajkot, Gujarat

I did my polo yearly service at rajkot on 27.01.2018. After that while driving in the night i felt that my car's head lights are giving less light. But i ignored it. But today when i tried to give self. It didn't happen. When i contacted volkswagen service centre, they told me that battery has to be replaced. But i didn't understand how my battery suddenly stops working after my yearly service. It seems something has been done to my battery. From a brand like volkswagen it is not expected.