You are a flight assistant. 
 USER: Hello. I am Deborah Harris.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I am planning to change an existing reservation, due to health issue.

ASSISTANT: Sure, I will help you. Please wait for a while.

USER: Can you please change my reservation?

ASSISTANT: Yes, definitely. Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no reservation existing on your name.

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

ASSISTANT: You are welcome, have a nice day.