You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I need to change my reservation due to urgent meeting, can you help me?

ASSISTANT: Sure, I am here to help you. Please let me know your name.

USER: I am Matthew Williams.

ASSISTANT: Thank you. Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: That's ok. Thank you for your help.

ASSISTANT: You are most welcome.