You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Could you please help me to change an existing reservation as my plan to meet my girlfriend got postpone due to my heath issues?

ASSISTANT: Sure, can I know your name please?

USER: I made a reservation by this name Sharon Mitchell.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Ok, not an issue.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your information.