Grand Motors Mannuthy — service fraud and misbehave

Address:

Thrissur, Kerala, 680019

The same problem i faced from grand motors mannuthy. I have oil changed from grand motors. But i did not fell engine smooth. While cheacked engine oil its colour dirty black. I contacted grand motors service engineer he says. The oil colour is black... I shocked. I asked which brand oil you using they told its specialy made from bajaj.
Why they doing like this...