You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am David Hill.

ASSISTANT: How may I assist you now?

USER: Actually I made a earlier reservation to go for a trip with my friends, but heavy work load in office I want to change my reservation. Can you please help me?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: Ok.

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

USER: Ok, no problem. Thank you.

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