[Sticw]

Why is there "unauthorised access" when bank gave him access.

I really have problem understanding this. A hacker who is not given access and hacks into the system gains unauthorised access.

Here the student was given access to the data. His access is already granted and authorised by the bank.

Friend, you a bit like arguing for sake of it. 

Access given doesn't mean you can do anything. He accessed data for no official reasons. 

Just like in army you are issued weapon and rounds for live firing. You are authorised and given access. You shoot someone with the round, you are at wrong.