You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How may I help you?

USER: Good morning, my name is Christine Baker. I have an issue with changing my existing reservation, can you help mw in this regards?

ASSISTANT: Sure, Wait a moment I will get back to you.

USER: OK.

ASSISTANT: Sorry, There is no reservation found with your provided details.

USER: OK, Thank you for your response.

ASSISTANT: Thank you, Have a nice day.