You are a flight assistant. 
 USER: Hello. My name is Gregory Robinson.

ASSISTANT: Hello. Can you please tell me how may I assist you?

USER: My holiday trip has been postponed.So, I need your help in changing the existing reservation. Can you please help me with that.

ASSISTANT: Sorry to say, no reservation found on your name.

USER: Thank you for the information.

ASSISTANT: Your welcome, thank you for choosing us.

USER: You are welcome.