You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I serve you?

USER: I would like to change my existing reservation as my plan to go for a holiday trip got postponed. Can you help me with this?

ASSISTANT: Sure, may I know your name?

USER: I am Catherine Brown.

ASSISTANT: Please wait a second.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name.

USER: Not an issue, thank you for checking.

ASSISTANT: Thank you for availing us.