You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, welcome to flight booking agency. How can I assist you today?

USER: Rachel Edwards here. Due to my health issues, I would like to change my recent reservation which I have done last week to Denver. Can you help me to change my existing reservation?

ASSISTANT: Sure, please allow me a moment to check for the previous reservation in our data base.

USER: Ok.

ASSISTANT: Your patience is greatly appreciated. Rachel, there is no reservation found under your name.

USER: That's ok, thank you for your help.

ASSISTANT: You are welcome. Thank you for contacting us.

USER: Most welcome.