Draught proof windows

Two of the windows (PVC double glazed) at the front of my house seem a little draughty - is there anything that I can do to sort this out.

Is there such a company to come out and sort it out for me.

I have tried putting the foam seal around the windows but has not made much of a difference

maybe the gap is between the wall and the frame..not the window itself? try tape a long piece of paper around to pin point where the coming thru.