Account holder is the maximum level for account management, an account manager gives almost the same level of access as an account holder.
What you need to do is speak with the Loyalty team, the number is on the letter, email and text you've been sent or call 0800 800 150, tell them you didn't initiate the switch and to stop it, BT have the ability to block the takeover/transfer.
You have until 2pm the day before the switch to stop it, after that it's past the point of no return and you have to have a new order raised to return, so act quickly.
