You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I am Rebecca Hall. Due to some issues I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I will help you. Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your given name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thanks for choosing us.