You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Emily Johnson.

ASSISTANT: How may i serve you today?

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

ASSISTANT: Sure, just a moment I will check the reservation list.

USER: Ok.

ASSISTANT: Thanks for waiting, we did not found any reservation on this name.

USER: No issue. Thank you for the information.

ASSISTANT: Thanks for approaching us.