Mazda CX-5 2.5 AWD False advertising of fuel consumption

I bought a new Mazda CX-5 2.5 AWD on the 15th of Aug from CMH Randburg. Their advertising claims fuel consumption of 7.3 liter per 100km on a combined average cycle. I've been driving the car for about a month and a half and been using the highway and urban driving and I am constantly getting an average of 11.3 liter per 100 km's. That is roughly 55% worse than advertised and there's no end in sight. The sales person told me it would come down and that the vehicle still had to become loser etc. After about 3000 km's, this should start to show, but it isn't, not at all. The average from day 1 is still 11.3 liter per 100 km. I would've never bought the car if I knew this would be the case and I'm very unhappy about it.