You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: On whose name, the reservation has been made earlier?

USER: My name is Jacob Green.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for your time, there is no active reservation found in your name.

USER: That's  fine, thank you for your service.

ASSISTANT: Thank you for choosing us.