This would seem very insufficient to CIC would be my guess. If I were reviewing your file I would definitely like some sort of history. How would I know where you got the money from? Is it just quick loan deposited in your account by a friend to make your profile look good or something? Do you get the gist of what I am trying to say?Yes just the current balance.
Bank said that that is the standard official letter they can give. They can't give past 6 months average balance as they don't have authority to do so.
Maybe you can ask for a letter listing the end of month balances for each of the last 6 months for your account? That shouldn't be too much of a problem would it?