Vodafone scam

I used to be with Vodafone but switched a few months back to a different provider, when they rang about a potential issue with my Vodafone account I was suspicious but still needed to check in case their were issues with my handover. When I rang them I was asked my first and last name, which seemed weird seeing as those details are typically attached to the phone number when setting up the account so they should have had them. I hung up on the excuse of being busy and then attempted to call back which did not work, as it stated the number I was rung on was not in use.