TVS Motor Company — wrongly charged for the manufacturing default

Address:

407/1, Gurgaon, 122001

I have purchased tvs jupiter two years back. I am complaining from last 1.5yr or in every service that scooty mileage is very low even less than 30km/litre but the company is claiming 62km/litre.
But in last service when warranty part is over they suddenly said it is your carborator issue thats why it is not giving mileage and they have charged 1633/- inclusive of tax for changing the carborator.
Even i said this is your manufacturing default but they didnt listen. I also raised complaint on phone to their centre, they said we will call you in half an hour but still no response from their side.
This is highly unethical to charge from customer for their manufacturing defaults.