Well, since you have a 2005 X3, you are stilll under the 4 year 50,000 mile factory warranty.
I suggest you let them do whatever they say needs to be replaced under warranty so that that problem is solved.
Let me remind you things under warranty are free. So that means you don't have to pay for whatever they fix to your car just as long as it doesn't pertain to your tires.
Never heard of this problem, but I'm sure your dealership knows what they are talking about when replacing that light switch, it may have caused a short or blown a fuse.
Sooo yeah, have the dealer replace it at no cost to you.
Have a nice day.