You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

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

ASSISTANT: Sure, we are here to help you. May I know your name?

USER: My name is Gregory While.

ASSISTANT: Ok, wait for for some time I will check the reservations on your name and get back to you.

USER: Sure, I will wait for your reply.

ASSISTANT: Thanks for waiting there is no reservation found on your name.

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

ASSISTANT: Thanks for contacting us.