Xenon Headlamp Range Adjustment is computed out by the HRA control module, it utilizes a front and rear level sensor. Could be a sensor problem. I have only had a problem with one car, and it was in an accident, the body shop didn't have the front sensor correctly installed. It is diagnosable with the Star Diagnosis tester. Have your dealer check it out for trouble codes. This is not a manually adjustable system, all you can really do is make it work correctly.....Gilly