The bank automatically applies the most expensive exchange rate. The trick is not to pay the dollar balance of the statement with pesos, but with your own dollars purchased through another means at a lower price.
Many people, in fact, are also using this mechanism before traveling. Pre-purchase the dollars you plan to spend abroad with the card in order to ensure the current MEP exchange rate, thus covering yourself from a possible new devaluation. The key is that the "tourist dollar", with its 60% surcharge, is applied only when a consumer pays the dollar Balance on their credit card statement with dollars.