You are not totally out of luck. I did the same at first but also used the electronics from the used switch as well. I posted that mod here:
http://e84.xbimmers.com/forums/showp...1&postcount=57
In my case the switch I got was for non-zenon lights but everything else was a match (fog lights and rain sensor). So I just used the electronics board. The leveling control is ignored and now you have the backlighting.
If you swap boards check the soft button height on the boards as they may be different between switches. If so you will need to swap the "block" between the button and board. One can also very easily disassemble the leveling control and put the blank plate from the original over it.
I.e. do not be afraid to totally disassemble the switch and mix and match.
That all worked great but I also happened to find a second switch that was the correct match sans the chrome knob. I just swapped it.
Oh, I paid less than $15 for each switch including shipping
.