You are a flight assistant. 
 USER: Hi. I am Susan Adams.

ASSISTANT: Hello, what can I do for you?

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

ASSISTANT: Sure, give me sometime to check and revert to you.

USER: Ok.

ASSISTANT: Thank you for your time. Unfortunately we didn't found any reservation according to your name.

USER: No issue. Thank you.

ASSISTANT: Thank you for contacting us.