You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Jack Wilson here.

ASSISTANT: How may I help you?

USER: I want to change my existing reservation due to my grand father health, will you help me on that?

ASSISTANT: Sure, give me a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: It's ok, no problem.

ASSISTANT: Thank you for reaching us. Have a good day ahead.

USER: Thank you for your information.