You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I render you today?

USER: I am Mark Clark. I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, we are glad to help you.

USER: Thank you.

ASSISTANT: Ok, please wait for a while. I will with the reservation list and revert to you.

USER: OK.

ASSISTANT: Thank you for waiting. There is no reservation found on your name.

USER: That's fine.

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

USER: Thank you for your information.