Bajaj Platina — less mileage than promised and billing

as company shows 108 km /litre but it never give 80km/l in any condition there is some procedure to check product mileage that sold in standard condition i don"t think it gave that promised mileage in any condition and second company gave bill or rs 37484 and take by check 38000 and said remaing 514 rs consist 160 ott slip that was not given to me and rest was commision to prepare rc from rto although the rto given the number series to dealer dealer is sanjeev bajaj bhilwara rajasthan