Update on Amex. I paid a tab using my US Amex card last month. The charge appeared on my statement as pending for a number of days then didn't show up at all on my AMEX online account. For about a month. At the end of the month the charge showed up at official rate and was cleared through my credit card company. A week later a rebate was issued that brought it up to the dolar turista rate, I'm assuming. 1ARS=$355USD at the end of February. I hope this helps. Looks as though AMEX is boarding the dolar turista but it's not as quick a turnover as VISA, which changes from official to turista as soon as the charge moves from pending.