How to adjust the nearside headlight beam left to right on my Citroen C3?

The garage have told me how to adjust the headlight beam of My Citroen C3 up and down but not left to right. I asked them to adjust it (it was lighting up the fields at the side of the road but not much of the road!) which they did but not by enough and they also either took off the headlight seal and didn't put it back again properly or knocked it loose. The end result is I have a headlight full of water with orange from the bulb stuck to the inside of the lense. Nobody else had been enywhere near it. I am now wondering if they could have interfered with it while adjusting the headlight?