Fault not being fixed despite numerous attempts

I have been having a problem with the front right dim light of my Golf 6 for more than 1.5 years now. Each time i take it to Lindsay Saker (I have taken it few times so far), they tell me that the problem has been fixed but all that is done is a bulb is replaced. However, this is not normal as the bulb should not be burning out every few months so something else is causing this. I did mention this to them but I don't think they have investigated sufficiently to fix this problem once and for all. Right now, the bulb has burnt out again but I am not sure about taking my car back to Lindsay Saker.