Confused with adverti*****t and problem on car

I bought a mahindra 3x0(mx3) in July this year and within the first week the stop and go function switched off my car in peak traffic and it didn't want to switch back on automatically, i had to struggle two and three times to start my car during these events. Now i hear it is a software problem Nd i can't drive without try the fan running all the time. It's been a month now and there is no news about a software update. My car's fuel consumption is at 10.2km/l where it is suppise to be about 18km/l, if I know i would ait with a brand new car with this bad fuel consumption I would never have bought it. In my opinion we are blinded by false advertising saying that the fuel consumption is 18km/l but in reality it's 10.2km/l