Maruti Suzuki — Very poor average-high fuel consumption

I Purchased Maruti Suzuki SWIFT Registration no GA07E8528 from Chowgule Industries Ltd Panaji GOA on 31 March 2013.At the time of purchase, I was informed that the car will give me a mileage of 18.6 km/ltr on highway and it will give me a mileage of 15.6 km/ltr in city running. These figures are also shown in the literature. On running the car for three months, I noticed the car average not even 10 km/ltr.

At the time of first service, I had pointed about the low mileage to the engineer concerned. No improvement was noticed. When I Pointed this again after the servicing, I was informed that the mileage will improve after second /third servicing.
No improvement has been noticed even after third servicing as the mileage is as low as 9/10 km/ltr in city running.

You may please look into and get the car checked up and show me an average mileage of 15 km/ltr in city running..
Hoping for quick action.
THANKING YOU
(B.S.BHALLA ) WG.CDR
RETD