You are a flight assistant. 
 USER: Hi. I am Sarah Lopez.

ASSISTANT: Hello Sarah, how may I assist you?

USER: Due to hot weather I want to change my existing reservation can you help me with that?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry Sarah, there is no reservation found on your name.

USER: Thank you.

ASSISTANT: Thank you, for contacting us.