New car with multiple problems!!!!

I bought a brand new Audi A3 Stronic car in February 2014. Four months later (in July) the car wouldn't start! I called Audi assist and the came and jump started the car and asked me to bring it to Audi westrand- which I did. After checking my car the whole day, they told me they couldn't find anything wrong with the car! In January the start-stop system on my car stopped working. Again I called Audi assist and they told me to bring in the car to Westrand Audi, which I did. Again they checked the car and found NOTHING!! I don't use my car for business but this car is on 60 000km, but when I compare the km travelled on my tracker statement vs what the odometer is showing- there's a huge discrepancy! This clearly means there's a fault with the odometer! Last night my car showed a message saying the gearbox is non-functional and the car stopped in the middle of the road! Again when I call Audi assist I'm told to take it back to Audi westrand! I left the car with them today but the service there was terrible! They even adviced me to complain to the head office as they can't assist me any further! I am furious, I'm not getting my money's worth. I bought this car brand new now this????