You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: Actually, I need change my existing reservation which is done recently due to health issue, can you please help me out/.

ASSISTANT: Sure, may I know your name?

USER: Sure, my name is Nicholas Harris here.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Sorry Nicholas Harris, no reservation is available by your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.