You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I be helpful to you?

USER: I am Karen Nelson and I just want to change an existing reservation due to my exams got post pone.

ASSISTANT: Sure, please wait for a second. I will get back to you.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found with your given name.

USER: Ok, no issue.

ASSISTANT: Thanks for approaching us, have a great day.

USER: Thank you.