If you are thinking of signing up to vodafone, CHECK THESE SITES FIRST:
This is Money: Vodafone complaints
Trust Pilot: Vodafone reviews
Money Saving Expert: Wrong Vodafone bills
The Guardian: Vodafone billing chaos
Or google "Vodafone billing problems" and find many more sites with the same story.
If you still sign to Vodafone, you have been warned.