You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I wanted to change my reservation due to my planned programme got postponed. Can you help me is there any chance to change my reservation.

ASSISTANT: Sure, I will help you with that. May I know your good name please?

USER: I am Timothy Mitchell.

ASSISTANT: Ok Timothy, please give me a moment. Thank you for waiting.

USER: Ok.

ASSISTANT: Sorry Timothy, there is no reservation found with your name.

USER: It's ok. Thank you for your help and valuable information.

ASSISTANT: Your welcome. Thank you for reaching us. Have a good day.

USER: Welcome.