Cannot fix the car

I bought a Golf GTI, collected it on the 07 August 2015, on my way home I filled the tank as I was going to Limpopo, before I reach Hamaskraal it started to show the engine light and started losing power when I accelate, the light went off and come back again the following day, I sent VW an email telling them that the car that I just bought was not good, they booked it for a service, I went to fetch it but before I got home the same thing happened again, I called them and the booked it for another service, it spent 2 weeks with them and they called me to say my car was fine, I drove it home and before I reach home the light came on again, and it cutting power when I accelerate, I really don't understand because they never fixed it all they do is to inspect and telling me that it has low fuel pressure, I cannot really continue paying for the car that has a problem that they can't even fix as a dealer, its really disapointing, I did not cause the problem I got the car with it