You are a flight assistant. 
 USER: Hello, I am Stephen Campbell.

ASSISTANT: Hello, how could I assist you today?

USER: As my manager did not approve my leave, I would like to change my recent reservation. Can you help me out?

ASSISTANT: Please wait for a while.

USER: Sure, take your time.

ASSISTANT: There is no reservation found with your given name in our data.

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

ASSISTANT: Thank you for availing us.

USER: Welcome.