You are a flight assistant. 
 USER: Hi. I am Betty Jackson.

ASSISTANT: Hello, how may I serve you?

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

ASSISTANT: Sure, let me check the reservation list and get back to you.

USER: Ok.

ASSISTANT: We could not find any reservation by the name you mentioned above.

USER: No issue. Thank you.

ASSISTANT: Thank you for approaching us.