Im sorry this happened to you. Are you certain the fake cash was from the ATM machine...? What were you paying when you realized this... or did you yourself discover the fakes once you left EZE...? Did anybody else handle the cash before the fakes were brought to your attention...?

I dont mean to doubt you... and fakes in ATM machines are not impossible, although it is a very rare occurence. This is because ATM's are loaded by at least 2 (two) bank staff, so both would almost certainly have to be in on the scam to have this work... also, an offsite ATM location such as EZE has further issues that involve more staff in the loading process because, among others, this location gets provided with cash from an armoured truck service so when the ATM itself if loaded, even more folks are involved in the process.

In many cases, folks take cash from an ATM and they go into a store or want to pay a taxi, in most instances, it is at the time of the payment transaction that their bills get swapped for fakes....

Regardless of what happened, Im very sorry you have had this inconvenience and hope it doesnt ruin your overall trip experience.