How te reset the auto-headlights sensor?

[Roadster]

I had my windscreen replaced at an aftermarket specialist as requested by my insurance company. Job well done and no complaints but... the headlights automatically turn on when necessary but never turn off automatically unless manually. When I called the company that did the replacement, they told me to have the light sensor at the top of the windscreen reset at my BMW dealership (at installer's cost).
Is there any way I can do this by myself by pushing some weird knob-combo on the dashboard or do I have to drop the car in at the dealer just to have this sensor reset? I'm not in for service in the coming months so no planned visit to the dealer in the near future...
Thanks.