You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am David Lewis here. I would like to change my previous travel dates. Can you please help me with changing my existing reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you for considering my request.

ASSISTANT: Please wait for a moment.

USER: Sure, I will wait.

ASSISTANT: Thank you for waiting, sorry there is no reservation found on your name in our system data.

USER: Not a big problem, anyway thank you for the information.

ASSISTANT: Thank you for reaching us, we hope see you again.

USER: Thank you for help in searching.