You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: My name is Michael Clark, can you help me to change my reservation?

ASSISTANT: I am happy to help you with that. Please wait for a while.

USER: Ok, take your time.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: Ok, no problem. Thank you for your help.

ASSISTANT: Thank you for reaching us.