I would say that they are specific to an employee (within a given frame). At our place (and it's not a bank) we all have passwords to get into our own accounts, and it's a serious disciplinary offence to give my password to someone else.
If you are thinking of pursuing unfair dismissal, your staffside rep would be able to get this information for you. All material documentation has to be shared with you if it's being used as evidence against you.
However, it's not just that form you should be concerned about - I am certain that you will have a policy at the bank about information governance, confidentiality, etc. - that's what you have transgressed - you need to get a copy of that and study it carefully.