You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I have to change my existing reservation, due to sudden change in the health condition.

ASSISTANT: Sure, can you please provide me your name?

USER: My name is Michael Roberts.

ASSISTANT: Thank you. Please wait for a while, let me check your reservation status in our database.

USER: Sure, take your time.

ASSISTANT: Sorry, I have not found any reservation under your name in our database.

USER: No issue, thank you for the information and your time.

ASSISTANT: You are welcome and thank you for choosing us.