I am currently going through 4 months of back and forth pain in my behind with movistar. Had them for 1 year and the service was fine until suddenly it wasn't, and to sort it out has been a disaster. Suffice to say i was without Internet for more than 3 weeks and movistar had no idea why and seemingly no sign of it getting fixed, and frankly didn't seem to care. So I closed my account and returned the hardware. 4 months later im still getting bills and trying to get that sorted too (the people in store are no help, the helpline service only is spanish since i closed my account, i tried posting on their facebook and website etc).
Now I'm with Vodafone and its like night and day. I had a problem with my bill and without even asking the cust rep they refunded the difference, fixed the problem and gave me some compensation. Their package is much better value imo too. Their English customer support is 100% better in every way which makes a huge difference when you're still learning espanol...
The trick is that movistar own the national network that the other companies use and its evident that movistar don't allow them full access (eg i have both fiber and adsl lines but Vodafone are only allowed to give me adsl. During the transition the mst technico would take weeks to come do his work and do it half assed and the vf guy was the opposite). I think jazztel are the only company that skip the mst network, so can provide equal support for setting up and problem solving. Anyway, despite the movistar carryon, vf were obviously trying their best to give me good service.
In summary movistar bad, Vodafone good (fyi I've friends who are having similar problems with orange)