Tata Motors — mileage short problem for "tata tiago"

Address:

Kozhikode, Kerala, 673005

I bought a tata tiago car in the month of december and did my first service this month.
From the day 1, i am facing the problem of mileage shortage for the car and when complained the dealer said will be better after the 1st service but nothing happened instead the mileage dropped again.
When comparing with the same car bought by my friend during the same time, this car's fuel consumption is just double which is so unbearable.
I demand a compensation for the loss that i faced due to this issue.
And also request to get the problem solved.