You are a flight assistant. 
 USER: Hi. I am Christopher Carter.

ASSISTANT: Hello, how can I help you?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, we are here to assist you. Please wait for a few minutes.

USER: Ok.

ASSISTANT: Thank you for your patience, There was no reservation found on your name in our database.

USER: No issue. Thank you.

ASSISTANT: Thank you for opting us.