Okay so I think the banking system should be more realistic.
First we need interest, it is a certain must. Also, we should have some other things.
We should only be able to use banking commands at certain areas, (ATM's and Banks) which are define by a lot flag.
At a bank all banking systems will be available, such as Balance, deposit/withdraw and history (like a mini statement).
At an ATM, you will be able to see the balance of your account and withdraw up to 300vT (in england max to take out is £300.)