Describe a time where you failed, then came back to succeed
Have to describe a bad incident and how you overcame it.
Tailor your response to focus on how you were able to recognize your error and then took action to turn it around and alleviate the situation. Since this is a sales rep interview, it's probably a good idea to highlight your communication skills if possible.
Advise a time that I had to use my interpersonal skills when assisting another employee. Give example of how I handled an irate customer. Give an example of when you could not help a customer. Quick answer: Never. Never advise a potential employer under any circumstance when you could not assist the customer. It's a trick question.