Change fees for my international flights (SCL/EZE-USA) have been $300 in both Y and J for a while now.
However, checking
https://www.aa.com/i18n/customer-ser...oter#ticketing for the first time in a very long time, I see that they now say:
Voluntary change to ticket before day of travel
$200 - domestic travel
Up to $750 - international travel (bolding mine, obvs)
For all classes.
So, we here won't know if they were supposed to charge you $300 or $500 or something more, since there's no published definition. I suppose in this case AA would say that you should be happy they didn't charge you $750! :/