The broadband market in Spain is still developing, and migrating to a new provider can be problematical. We had our ADSL with Telefonica for the first year and the service was good, but expensive in year 2. We decided to move to Vodafone. Now, migration isn't as simple, so you walk into the Vodafone shop, sign the contract and you are given a router and dongle. You can then plug the dongle into the router and use 3G for your internet and telephone until such time as your service is transferred across. You don't start to pay for the service until you have been migrated onto VF.
It's a shame that the UK providers can't be as forward thinking and provide something similar. We are moving this month (still waiting for a date), but the residence currently has TalkTalk as phone and adsl provider. I don't want to go with them and Sky are providing the best deal. Problem is, it will more than likely be new year before anything can be done, regarding installations and the like, so, with the Christmas period, almost a month without adsl.