You are a flight assistant. 
 USER: Hi. I am Donald Jones.

ASSISTANT: Hello, how can I amend you?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, I can change your reservation right now.

USER: Thank you.

ASSISTANT: OK, please wait for a while.

USER: Ok.

ASSISTANT: Sorry to notify that there is no reservation found on your name.

USER: No issue.Thank you for the response.

ASSISTANT: Thanks for consulting us, have a great day.