You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I help you?

USER: I want to change my existing reservation, due to postpone of my examination. Can you help me out?

ASSISTANT: Sure, I can help you in that.

USER: Thank you.

ASSISTANT: Can you provide me your name to check your reservation status?

USER: Sure, my name is Katherine Jackson.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Thanks for your time, there is no active reservation found with your name to change it.

USER: No problem, thank you for your information.

ASSISTANT: Thanks for approaching us.