"Employers hiring bank tellers are looking for candidates who can provide superb customer service regardless of stressful circumstances. Expect a lot of situational or role-play questions that will assess your ability to diffuse unsatisfied customers and handle money professionally. In addition, bank tellers must also be comfortable with counting and handling bills efficiently and accurately, so come prepared to answer a mental math counting teaser."
How did you handle an irate customer?
Listen to them, understand their questions or concerns and proceed accordingly.
Yes you listen. Then relate back to them what they are concerned or upset about. Let them know you can help and if you can't personally, you would like to share their concern with someone that can help further to resolve their issue immediately.