Headlight beam scatter

Hi Folks, been a member for a while but this is my first post.I know there is a wealth of passat experience out there so hope to tap into it. I have recently bought my third b5 passat, 99 reg 110 with 74k and very happy with it. This is the first passat i have had with the front fogs in the headlights. The problem i have is beam scatter. On dipped beam it is very slight at the edge of the beam, vertical lines as in the headlamp lens. On main beam it is very pronounced and there is a black line down the centre of each beam. The bulbs are standard halogen, h7 for the dip and h4 for the main beam and fog. The height and spread of the beam is fine. Never had this on previous passats which always had 2 h7 bulbs. I definitely cant live with this so any ideas as to the cause. Thanks in advance for any suggestions.