Reviving this thread because I made a charge in Argentina with my US issued Amex and its been quite some time and the Exchange Rate adjustment has still not posted. From the last data points, it would seem that the correction/refund of the rate difference posts somewhere around 2-5 days after the full original charge posts.

To be specific, I made a AR$ denominated charge for purchase of Buquebus Ferry Tickets, the charge posted on October 3rd, with the horrible official exchange rate. One full week later (today is 10/10), I have yet to receive any adjustment/credit..... wonder if I need to call AmEx and ask...? I thought about calling Buquebus, but they arent responsible for this since it is a Government issued difference which should process directly to the original form of payment...... thoughts...??

Thanks,
Alex / Gaucho100K