Honda Shine — very poor mileage

Address:

Karnataka

Dear Sir,
I have purchased Honda Shine on[protected]. from the time of purchase i have been getting very poor mileage. I complained the dealer, who assured me that after the 1st servicing things will be fine. I have done initial 2 free servicing on time. The mileage has dropped from 44kmpl to 38kmpl. Today when i gave for 3rd free service and raised the issue, the works manager kept on arguing that the quantity of petrol at the pumps these days is not correct so i m getting poor mileage. I am an engineer and take utmost care of my vehicle. Avoid constant gear switching, drive in economy mode and switch off ignition at traffic signals. still i get only 38kmpl mileage.
please suggest whom should i approach. should i go to consumer court or something?