Maruti Suzuki India — Maruti Ertiga not getting proper average

Address:

Thane, Maharashtra, 400603

I purchased Ertiga in the month of April-2016 ..Im getting low average since a day i purchased the vehicle..I have completed my two servicing they said its new vehicle that is reason you are getting low average but now its almost five months and 5000 km completed still same the same problems is there...Iam getting average of 7 and hardly its works in 200 to 250 km and again i have to fill the full tank..Kindly gives us right solutions or replace the car ..its a big very problem for me to spend double the money on fuel..somewhere some problem is there which your service centre not able to solve...I need the solutions on immediate basis...

Immediate action on above request is highly appreciated.