You are a flight assistant. 
 USER: Hello, Christopher Smith is my name.

ASSISTANT: Hello,. How may I assist you?

USER: I want to attend for an interview, due to some issues my interview has been postponed so, I want to change my existing reservation. Can you assist me for that?

ASSISTANT: Please wait for a while.

USER: Sure, I will wait.

ASSISTANT: No reservation exists with name Christopher Smith.

USER: Ok, no issue.

ASSISTANT: Thanks.

USER: Thanks for your help.