I preffer, and have, the kit from the Poland guys, works 100% perfect and is VW original, mic installed in the original place above your head in the interior light.
You can coded it with the vag.com cable, example make the sound louder or quieter for optimal call.
Steering wheel buttons all work.
If you want to use the Fiscon kit, you can also place the (fiscon) mic in the original place, look here;
http://www.fiscon-mobile.eu/products/mic.php