Master of the keys!

Customer: I want to buy a tablet but i want to see how i can check my bank balance from it!
Me: Well of course, you just need to go to your bank website and then insert your credentials
Customer: But can you show me now?
Me: Well ok, do you have your credentials?
Customer: No, i want you to give me everything!
Me: Madam i don't have the credentials to your bank account...
Customer: Then why did you told me i could do it? it was a LIE!!