You are a flight assistant. 
 USER: Hi, I am Andrew Clark.

ASSISTANT: Hello Clark, how can I help you?

USER: Owing an emergency need to change my existing reservation, can you help me with it please?

ASSISTANT: Sure, I will help you in this. Wait for a moment please, to check your reservation status.

USER: Sure.

ASSISTANT: Clark, I did not found any reservation with your name.

USER: That's ok, thank you for the response.

ASSISTANT: My pleasure, have a nice day.