If my account was opened using an out of date passport does this make the credit agreement void It is a joint bank account that I was added to and have now been left with the debt?

Question continued ...When I split from my ex partner we had the problem of a joint bank account. We tried to have either of our names taken off the account but ran in to problems when they refused me this service due to an out of date passport. I then realised that my name was added to the account (which was already established in her name) with said expired passport. Does this mean that I can deny responsibility for any of the remaining debts attached to the account because the agreement that I would have signed should be void as the documentation they used to open the account was invalid?