Tata Harrier XM (Manual)'s Fuel efficiency / Average has reduced from 15km/lt to 10.6 km/lt

When I had purchased TATA Harrier, for first 1.8 years, the SUV gave me fuel efficiency or average in the range of 15-18km/lt with and without AC. But now after 4th and 5th service, the average has been reduced to 10km/lt which is pretty bad compared to what it used to be. 

Probably it is by design or if at all service center might have done something crazy with it. If you own a TATA Harrier, what's been your experience? How much fuel efficiency are you scoring?