Worst mileage.

I have Tigor xt petrol driven 4000 kms done with 1st service. Mileage only 10 kmpl, worst performance, lags in 2nd gear, not happy with the service. Service people only trying to convince me, but not trying to get the issue and rectify. They ask me to drive only 50 to 60 kmph in the highways and so many terms and conditions to get mileage of 19 kmpl. It is not at all possible to follow them on the road..