HK-UMICH
I had the same problem, see
http://www.flyertalk.com/forum/Forum71/HTML/002485.html
I called CS, and Naomi very swiftly changed the price of my ticketing, and mentioned that the fare difference will be refunded into my credit card account (not in the form of vouchers).
There is no $100 change fee as long as your itinerary remains unchanged. However, as it is considered a new issuance, I will have to drop by a local CTO to be re-ticketed, and all these within 24 hours as the newly priced ticket is only put on hold for that time period. If you cannot make it in 24 hours (like in my case, most of the 24 hours was between Saturday midnight and Sunday!), simply call them again to have it extended a further 24 hours. But the new price is not guaranteed, so if at the time of re-ticketing the fare is gone, it's gone for good!
Enjoy your trip to Germany. I know I will enjoy mine to Italy. Afterall, I am flying American.
Cheers,
Maple
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Flew every one of those 25,000 Q-miles and onto 50,000! But is it worth it still?