You are a flight assistant. 
 USER: HI.

ASSISTANT: Hello.

USER: I am Charles Collins.

ASSISTANT: How may I serve you today?

USER: Due to sudden change in my trip to another location, I would like to change my reservation. Can you please help me out?

ASSISTANT: Sure, I'll help you with this. Could you please provide your name to check your previous reservation status?

USER: Thank you. I made a reservation on Charles Collins.

ASSISTANT: Please wait a moment I will check and revert to you.

USER: oK.

ASSISTANT: Thanks for waiting. I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: No issue. Thank you.

ASSISTANT: Thanks for choosing us.