I had Orange on my 8700f. I have now Vodafone. I can phone and use Internet OK. When it comes to default email address, it says an account already exists and Orange logo is everywhere.
In this case you'd have to remove the email account (association) on the Orange network, and then add it to Vodaphone. Can you log into your Orange BIS account, still? You might have to call them to do it for you. Sounds like the PIN is still associated with the Orange account...
Once it's released, then you can add it to vodaphone...
I will add that you may have issues with Orange....But if you are the original owner of the phone then you may get this sorted quickly....otherwise a little battle may follow.
I am on O2, but using a brandnew 8700v (Vodafone UK) Unlocked BB. Works great but never had any pre-registered email accounts to the BB....