You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I would like to change an existing reservation as my plan to meet my girlfriend got post pone due to my health issues. Can you help in change an existing reservation?

ASSISTANT: Sure, please wait a moment. May I know your name?

USER: I made a reservation by this name Mark White.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok, not an issues. Thank you for your information.

ASSISTANT: Thanks for reaching us.