You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: I want to change my recent reservation, because I am unable to catch the flight in those dates. Can you help me in changing my ticket?

ASSISTANT: Sure, I will help you with that. May I know your name for checking your reservation?

USER: Yes, my name is David Evans.

ASSISTANT: Ok, wait for a minute.

USER: Ok, take your time.

ASSISTANT: Sorry Davis, your reservation is not found in our database.

USER: It's ok, no issues. Anyway's thank you for the information.

ASSISTANT: Thank you for consulting us.

USER: You are welcome.