You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Larry Martin.

ASSISTANT: What can I do for you today?

USER: As my manager did not approved my leave so I want to change my existing reservation. Can you please help me?

ASSISTANT: Sure, I will help you to change your reservation. Can you give me some time to check your previous reservation?

USER: Ok, take your time.

ASSISTANT: Sorry Martin, there is no reservation is showing in our data base.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome. Thank you for choosing us.