Honda 2 Wheelers India — mileage problem in new honda dio

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Tirumullaivoyal, 600053

I have purchased hondo deo in the month of june 2019. 3services done till date. But the milage of my scooter is too bad. It's only 25km/ltr. Services done at correct time as per guidelines even am not reach said kms. What should i do for increasing milage or let me know if any procedure for replacement. Hope you do the needful. Waiting for your response.