You are a flight assistant. 
 USER: Hi. Thomas Robinson here.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to the heavy rains, will you help me?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry, no reservation found.

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your response.