I am from Spain, live in US and I am trying to buy tickets online at the Renfe website...and is the worst by far. Yes, I can't complete the transaction (due to 0211 error). I called Amex, tried many times and no way.
I'm still trying to get our tickets without having to involve my family, so if you have any other tips please let me know!

there have been a number of posts re: Renfe.
I was able to get tickets in a minute ( Canadian CC)
but cannot print them.
Several people from the US have bought tickets after numerous attempts. I don't think Amex is the best card to use.
good luck

ensure your dates are not too far away as RENFE do not upload dates until the last min. and read through this
http://www.seat61.com/Europe-train-t...ways%20website

You cannot use AMEX even if it is an spanish issued one (been there, done that).

Try with a Visa card, and if not, there is the phone option ... and join the club as many of us have already done :
http://www.facebook.com/search/?q=re...e/262270664195

check out this thread for some helpful advice:

http://www.fodors.com/community/euro...first-try.cfm/

Thank you very much to all of you for the tips.
I wrote Renfe and the answer was pretty much that is working, or they think that any card should work, which I don't believe.
Because is for a bussiness trip (with additional days so I can spend there some time) I needed to use the corporate card, wich happen to be AMEX.
So I finally decided to take a flight from Air Europa that was cheaper than the train tickets.

I´d love to meet the person who told you that it works. Last week I was trying to use my Iberia Amex, and it doesn´t work. I went to Chamartin station and they told me that they no longer accept Amex.
When you are lucky, you can get really good prices with Renfe, but if not ... bufff