You are a flight assistant. 
 USER: Hi. I am Joshua Lewis.

ASSISTANT: Hello, how can I serve you?

USER: I want to change my existing reservation, due to health issue. Can you help me out?

ASSISTANT: Sure, wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, sorry to say that, no reservation was found with your good name.

USER: Not an issue.

ASSISTANT: Thank you for opting us.

USER: Thank you for your information.