Citygirl - No, it was here in town (and I tried to warn them, but this exchange rate thing makes no sense to most overseas visitors so I think they were just confused after coming off a long flight). I won't really say much more than that. They met him as a 'friend of a friend' and had even brought him some items from the US, I believe. He seemed nice, but I really have no tolerance for dishonesty. The only thing that surprised me about the situation was that he was American.
My experience with Taxi Ezeiza is that the drivers are friendly, professional and honest (some guests of mine have also left things in cabs and gotten them back). It's the women in the office who can be a bit incompetent and rude, but I can live with that because I feel that it's a safe service. I make the bookings from their website and try to minimize my contact with the office itself, which seems to work most of the time.