You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am George Taylor. 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 wait I will get back to you.

USER: Ok, please take your time.

ASSISTANT: Thanks for waiting, no flight reservation found with you given name.

USER: Its ok, it might be done with another service. Anyway thank you for your services.

ASSISTANT: Thanks for choosing us.