You are a flight assistant. 
 USER: Hello, I am Margaret Lewis.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me with changing my existing reservation which was reserved last week?

ASSISTANT: Sure, please wait a minute.

USER: Ok.

ASSISTANT: There is no reservation with your name.

USER: No problem, I think there is problem when reserving a flight ticket. Thank you for your information.

ASSISTANT: Thank you for reaching us.