After trying for a few weeks, I just successfully transferred funds via WU from my US bank account. I've recently been wiring funds from Citi/NY to Santander/BA, withdrawing dollars, taking them to my change guy next door to the bank, and then returning to the bank to deposit pesos. When I first heard about the WU opportunities in early January, I googled for more information and stumbled into this thread (after not opening the forum in at least a year!) Thanks to everyone - especially stevinbsas - for all the worthwhile tips and details.
In addition to the issues everyone else has noted, I've been stumped for some weeks now by a problem others might encounter. So I'll document it for future reference here.
When I first tried to sign up, WU responded that my email address was already in use. I recovered the password but still encountered errors trying to log in. I finally called, and an agent reset the account so I could log in.
Thereafter, whenever I tried to order a transfer - via bank transfer or debit card - sooner or later I got a message C1992: "We're sorry, but we can't process this transaction. You can always send cash at a Western Union agent location." At times other errors appeared, but these were transient or I could work around them. But sooner or later the "sorry, we can't process this transaction" message ended the session.
2 different chat agents told me "Western Union is subject to a number of economic sanctions and restrictions imposed by the United States and other countries, and it appears based on the information that you have provided that the transaction might violate one or more of these sanctions programs." But they couldn't provide any more specific information, nor could they refer me to anyone who could.
Finally today, I carefully read the entire 45 pages of this thread, expecting to find the solution. When I didn't, I decided to begin at the beginning and created a new userid with a different email address, and this fixed the problem. Apparently the old account, unused in probably 20 years, was contaminated in some way that can't be fixed online or by the agents. Now everything works as described by the helpful foristas.
Btw, they charged $100 for a transfer U$ 2.000 from a US account to a cash pick up here. Still a net rate of 78,4 ars/usd without the hassle of importing dollars.