You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, may I know your name please?

USER: I am Alexander Collins.

ASSISTANT: OK, please wait.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation found with your name in our records.

USER: Ok, no issues. Thank you.

ASSISTANT: Most welcome.