You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Andrew Mitchell here.

ASSISTANT: What can I do for you today?

USER: Can you change my flight ticket reservation? As my travel dates for the business trip has been changed.

ASSISTANT: Ok, please wait for few minutes.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: That is not a problem.

ASSISTANT: Thank you for reaching us.