You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I render you today?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, may I know your good name?

USER: I am Karen Roberts.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

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

USER: Ok, not an issue. Thank you for checking.

ASSISTANT: Thank you for opting us.