You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: Owing an emergence, I want to change my existing reservation. Can you help me with it?

ASSISTANT: Sure, may I know your good name please?

USER: My name is Jack Thomas.

ASSISTANT: Ok, please wait for a moment, I will check and get back to you.

USER: Ok.

ASSISTANT: Sorry, no reservation found with your name.

USER: Ok, no issues.

ASSISTANT: Ok, thanks for choosing us.

USER: Thanks for the help.