Dear behuman,
Please accept my sincere apologies for the inconveniences you encountered - and thank you for your kind words. I am glad to hear you enjoy flying with us :-)
I was in touch regarding this topic with the respective departments and there are indeed a few cases where this problem can occur. It is mostly triggered by minor currency fluctuations that cause the respective amounts (authorized and charged) to deviate slightly. If this happens, the authorization is not waived automatically.
We are trying our best to find a solution to the problem. I would recommend contacting one of our service centers and take up the issue with one of our agents should this occur again. They can take up the case and expedite waiving the blocked amount.
Best regards from ZRH,
Nick