You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I want to change my existing reservation due to sudden change in my trip dates. Can you help me with that?

ASSISTANT: Sure,I will help you with that.

USER: Thank you.

ASSISTANT: Please wait for a minute. May I know your name please?

USER: Brandon Davis here.

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.