Angry customers should not knock the wind out of your sails. They belong to the bank, and you should count with the possibility of meeting them in your job.
Client is always right, at least the internal policy of every banking institution says so. Therefor you should never suggest arguing with the client. Show us that you know what to expect in your job, that bad customer behavior will not discourage you, that you will try your best to satisfy every client with your service.
In my previous job at AT&T, I was confronted with irate customers on a daily basis. People were not satisfied with their invoices, the money they had to pay, and they often blamed me for that. I always calmly explained them, in a simple language, why the numbers didn’t match their expectations. I maintained a friendly attitude, and it worked most of the time, as soon as they understood I was not their enemy, just an employee doing their job.
This is my first job application, so I do not have a similar experience. However, if it happened in a bank, I would try to understand the customer, listening carefully, and asking additional questions while trying to identify the real problem they have. I would definitely not argue with them. Anyway, I count with this behavior, and angry customers would not discourage me in job.
Verbal and non-verbal communication should correspond
If the interviewers felt anger, or envy, or other negative emotions in your voice, they would not hire you. Try to answer their questions calmly, with positive attitude, with enthusiasm, even if you have to speak about an unpleasant situation (dealing with an angry client, etc).