I have 2013 CC that exhibited the same issues in this thread. I went in for my 1000 mile courtesy check. Asked them about a software update, pulled up my VIN and sure enough there was one available.
However, he indicated it was not a public(?) update, but rather only for cars 'in inventory'. He asked me to explain the issue I was having, and I did the iphone pan L & R trick. He understood the problem and got authorization to try the update on my vehicle.
Sure enough it corrected the problem. Streaming in perfect stereo now.
The update # on my repair ticket is listed as:
91J7 2012-10-02 Update - RCD 510 (Premium 8) Radio Software (Inv_only)
So... give that a try at your dealership. You may have to ask nicely for them to do it on your vehicle, because as of now, apparently the dealer is not getting reimbursed from VW to perform this fix on customers cars, yet. I assume that will change soon. But mine was done at no charge to me, and I'm a happy camper now.
I just finished upgrading my Pandora and am ready to go!
Good luck...
Andy