Hi @Apollyon
You will receive that message when you have entered the security PIN incorrectly, I believe it is 5 times. You will probably need a PUK code for your number from Vodafone but if the SIM is locked, you will need a replacement SIM.
The best way to get this solved will be by contacting Vodafone, live chat should work well and be able to advise accordingly. Alternatively, you can always go through Twitter/Facebook social channels here: Contact Us
