>>>Is there a vodafone freephone number?
No. Your best chance of getting assistance is to call 191 from your mobile phone (with your UK card in it). As you're obviously using pay-as-you-go (rather than a monthly contract) it will cost you 25p per minute to talk to a customer adviser. (Automated services are free).
However it's not clear what type of Vodafone sim you've got. The options are here:
http://www.vodafone.co.uk/shop/get-a-sim-for-your-existing-device/
It's also not clear, from your post, whether your phone is locked to Vodafone or not. It's possible that the phone system sees Vodafone ES and Vodafone UK as separate providers.
It's also possible, of course, that there's simply no Vodafone 3G signal where you're staying. I'm in Suffolk and technology can still be very basic around here. There's a rumour going around though that someone in Southwold has invented something called 'a wheel' ;-)