You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Due to the sudden change in climate, my appointment with doctor has been postponed. So I had a request to you to change my existing reservation?

ASSISTANT: Sure, I am glad to help you. Please wait a moment I'll check your details and revert you.

USER: Sure, my name is Michael Green.

ASSISTANT: Sorry, I didn't found any details regarding your reservation.

USER: Ok, no worries.

ASSISTANT: Thanks for reaching us, have a nice day.

USER: Thanks for your valuable information.