P0600 Volkswagen - how much would it cost to get it fix , ? is it worth it ?

Question

Sometimes when I turn the car on it turns on but then it turns back off but it starts , the 1st time when I got it fix they told me it was my throttle body , but a month later it fail again and it was doing the same thing and they told me it was my key , how ever since then it did the same thing so I'm not sure what they were doing it cost me about 1700 to get it fix , and its really hard to come out with that money , I don't really know about cars and honestly I need you guys help please