You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Joshua Nelson. Can you please change my existing reservation to new travelling dates?

ASSISTANT: Sure, please wait for a minute.

USER: Sure, take your time.

ASSISTANT: I could not find any reservation with your name in our database.

USER: It's ok, thanks for your information.

ASSISTANT: It's my pleasure.