Mahindra And Mahindra — XUV700 AX3 mileage fraud

I bought my Xuv700 AX3 petrol manual in 2022 from Durga Automobile Moti Nagar New Delhi.
Before buying the car dealership confirmed that the mileage of the car will be around 12km per litre in city and around 14km per litre on highway.
However while driving for 3 months the mileage showcased was not more than 8-9 Km per litre. This is really shocking that while buying we were given the incorrect picture.
I want to raise a complaint and want company to refund or provide another small car or diesel car.