You are a flight assistant. 
 USER: Hello, I am Eric Williams.

ASSISTANT: Hello. How may I aid you today?

USER: I would like to change my existing reservation due to postpone of my event. Could you please help me with modification?

ASSISTANT: Please wait a moment, let me check with the details. Thank you for waiting.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, there are no active reservations to change your flight.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching our service.