You are a flight assistant. 
 USER: Hi. I am John Lee.

ASSISTANT: Hello. How may I aid you?

USER: I want to change my travel dates, due to some health problems I am unable to travel those dates, can you please change my reservation?

ASSISTANT: Sure, please wait a minute.

USER: Ok.

ASSISTANT: There is no reservation found under your name.

USER: That's ok, thank you.

ASSISTANT: Most welcome.