Suzuki Fourways terrible service

What a terrible experience. Bought a Suzuki Baleno, as they advertise that the fuel consumption would be 5.5 for AT. After driving for few days the consumption was 7.8!!! when I complained they did very little to help me. I was promised they would send me a letter in response to my complaint - a week later I am still waiting. I got a email form Suzuki SA asking me to rate the service, in the comments I indicate my problem, and I did not receive a call from them. I will be taking this matter to a legal advisor