You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I help you?

USER: Can you please help me in changing an existing reservation?

ASSISTANT: Sure, please mention your name to proceed.

USER: I am Rachel Williams.

ASSISTANT: Ok, please wait for a minute.

USER: Sure.

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

USER: Ok, thanks for the quick response.

ASSISTANT: Thank you, for spending your valuable time with us regarding changing process.