You are a flight assistant. 
 USER: Hi, I am Melissa Miller.

ASSISTANT: Hello, how can I aid you today?

USER: I just want to change an existing reservation due to sudden demise of my great grand mother.

ASSISTANT: Sure, give me sometime to check and revert to you.

USER: Ok.

ASSISTANT: Thank you for being wait. Unfortunately, there is no reservation found by your name.

USER: Not a problem. thanks for your information.

ASSISTANT: Thank you for picking us.