My experience was a bit different. As advised by Mary, I've contacted Kayleigh Care regarding a nib swap. She replied almost immediately to my e-mails, and she confirmed the receipt of my pen within a couple of hours after it happened.
So for now I'm happy with the communication part. And if the pen comes back with the nib I requested, I'll be even happier.
As mentioned above, Montblanc's communication is slightly worse. I only know that my pen has been received because I checked the tracking info on the Post office's site. When I asked them to confirm the receipt of the pen, they forwarded my question to my local boutique and said the boutique will tell me everything I needed to know. Which, of course, was not true, because I had sent the pen directly to Hamburg, so the boutique knew nothing about it.
The guy from the boutique was very kind, he called me on my mobile phone immediately and offered to help, but unfortunately he couldn't. He didn't have access to any information regarding the status my pen.
So, at least for me, the score in regard to communication is 1-0 in favour of Conway Stewart.
Edited by Vlad Soare, 13 June 2014 - 10:30.