That's what I posted on Saturday. One company cannot advise on what another company will or won't do.
The OP, hindsight is a wonderful thing, should have notified all relevant parties. Expecially friends, family and customers.
So the moral of this story is to log-in to one's PN account and check that the details are correct, including the phone number, before requesting any changes to the account, e.g. switch to a different broadband package, arrange a retention deal or migrate, otherwise if some of the details are incorrect then the account could be closed.
When I was with PN (BB only) support staff would always ask for my user name and some of the characters from the password if I called them but never verification of my phone number. If verification of the phone number was requested then the problems such as those suffered by the OP could be avoided at an early stage - it may not be "fool proof" but it could be simple to implement.