You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello,. How may I help you?

USER: I need to change my existing reservation due to postpone of my trip to Oakland.

ASSISTANT: Ok.

USER: Would You please help me with changing my existing reservation?

ASSISTANT: Please provide your name.

USER: Sure, my name is Amanda Edwards.

ASSISTANT: I regret, no reservation exists.

USER: No problem, thank you for the information.

ASSISTANT: Thanks.