I have started this thread in the General Chit Chat area of the forum as I hope it will get the most exposure.
I live in Spain and today I received a call from someone claiming to be calling from Telefonica/Movistar, saying they could help me with my bills.
He also kept trying to get me to say yes to changing something, but I couldn't quite understand what exactly, as my Spanish isn't quite good enough to fully understand everything that is being said, so I just kept saying that I didn't understand and in the end said goodbye, at which point I hung up the call.
I then checked the number and it was: 0054 351 413 2600
The country code of 0054 is Argentina.
I called Telefonica on 1004 and spoke in English to a representative, who said I had done the right thing as they know I speak English and will always speak to me in English, and will have my details on screen, so will not ask me for any password or personal details.
So... Beware of anyone calling saying that they are from Telefonica/Movistar. If you think the call is not legitimate, ask them to call back later or tomorrow and check with Telefonica/Movistar that they have called you.
And if the call number starts with 0054... then unless you know someone who lives in Argentina... then don't answer!