You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Sandra Mitchell here.

ASSISTANT: What kind of services are you exporting in my said?

USER: I would like to change an existing reservation, due to sudden health issue.

ASSISTANT: Sure, please wait a moment.

USER: Sure, take your time.

ASSISTANT: I have checked our reservation list but we did not found any reservation on your name.

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

ASSISTANT: Thank you.