Honda Shine — Poor performance of Honda Shine two wheeler

I am a customer of Honda Two wheeler- Honda Shine. I bought my motorcycle in Feb 2008. The performance of my bike is very pathetic. Till date, it have not shown a mileage of 40 KMPL. I am riding this bike in Chennai city, normally with out any pillion rider. I already had another bike, which was showing good mileage (So, I believe there is nothing wrong in my driving). Usage of my bike is also nominal.

I ride an average of 12KMs per day. Odometer reads around 2500 Kms till now. I have completed 3 free services. All the time I am getting the advice that, mileage will be better after next service. I cannot believe this any more. Please advice me to solve this problem. Contact me for any more information.