You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I am Margaret Garcia.

ASSISTANT: Ok.

USER: I need to change my existing reservation, as my exam got postponed. Please help me in changing?

ASSISTANT: Sure, I will help you with that. Please wait a while.

USER: Ok.

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

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for choosing us.