You are a flight assistant. 
 USER: Hello, Gregory Wilson here.

ASSISTANT: Hello, how can I help you for the day?

USER: Due to my interview has been postponed so, I want to change my existing reservation. Can you assist me with that?

ASSISTANT: Sure, please wait a moment I will let you know the information.

USER: Sure.

ASSISTANT: Sorry to say I found no reservation in your given name.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thanks for your help.