I am the main account holder not an additional account holder

With the email I received today saying VM will turn off additional account holders’ ability to log in, I am forced to try getting help here. 

I am told by VM that after 20 wars of being a customer and moving house 4 times in that time, that I am not the main account holder for my own account. I am baffled as to why this is, and obviously their customer serve reps are too concerned about breaching confidentiality to be of any help to me. Happy to take my large sum of money every month from my bank account of course,  but heaven forbid I should be able to control my own account with them. 

Anyone had any success in convincing VM that they are in fact the main account holder of their own account?