Which route/airline did you book and which class?
Rebooked GRU-FRA-BER to GRU-ZRH-BER

How many pax and how many award miles?
1 pax, "old" award (71,000 miles). Rebooking fee 50 € + 19 € difference in taxes minus 40 € refund

How many days/weeks/months did you book in advance?
About 7 months in advance

Have you been able to book your preferred dates of travel?
Yes

Were you happy with the award booking procedure (e.g. online/by phone)?
By phone. Not very straightforward, see below.

How often did you have to check/call until you got the seats?
Tried for 2 weeks to change an award booked in June 25 for travel next year. Online and by phone, no agents could see availability on GRU-BER via FRA or ZRH due to a married segments issue, even though multiple J seats were available when searched separately. I called at least 7 times over the 2 weeks. Agent expertise varied widely: some said nothing could be done, others only found availability with long layovers in ZRH or FRA and one even claimed I needed more miles to change. The final agent who seemed very competent managed the rebooking with my desired segments and explained there are ways to "trick" the system into confirming the desired segments but it's not often done by others.