You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am Helen Collins. I want to change my existing reservation, due to sudden demise of my grand father. Can you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Sure, take your own time.

ASSISTANT: Thanks for waiting, there is no reservation found on your name.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for choosing us.