Well my mole at VW customer services....alight Jimmy, has just called back after mentioning to him about the climate windscreen when speaking to him earlier. He said after investigation with marketing, that it is indeed due to the additional radiated interference that would disrupt the phone signal in the car, and so it therefore needs to be routed through the cars aerial (which is part of the upgraded phone package). So a chocolate fish to p3asa

However, when asked why on the Irish price list for the GTi/GTD, it seems to allow you to spec the heated windscreen on its' ow, in fact the Irish price list just says:
HEATED AND INFRARED REFLECTING WINDSCREEN €350
Heated laminated glass
Note: Available from week 15/13
To that, he didn't unfortunately have an answer ?