Hyundai Motor India — Fuel average

Address: Kamrup Metropolitan, Assam

I took i20 elite sports, while taking the car I was told that you will get average of 18 km per ltr but I am getting 10 and on first servicing when I told that I am getting average of 10 they said after second servicing you will get 18, but it was not mentioned anywhere that after 2nd service it will improve. Pls try to solve my problem of fuel average as now I am feeling I was cheated and this I never expect from hyundai as before this I was driving i10.