Thanks for this discussion. Moral... have you started flying on the ticket? I am trying to keep it clear in my mind when repricing, change fees, and surcharge/taxes are charged.

Based on my experience and reading the Oneworld rules in our sticky :

I "think" repricing happens if you have not flown yet. I "think" change fees happen when you change flights (not for simple date or carrier changes) after starting travel. I "think" surcharge/taxes can be charged on any change after starting travel - this seems to be case you are pursuing. Hope you find out that I am wrong about the surcharges/ taxes for date changes only.

Please report what your results are. Thank you.