You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Here Debra Davis. I would like to change my recent reservation due to some personal problems.

ASSISTANT: Sure, I will help you out with that.

USER: Thank you for positive response.

ASSISTANT: Please give me a moment to check your reservation status.

USER: Sure, take your own time.

ASSISTANT: Thank you for waiting, we couldn't find any reservation on your name in our records.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Welcome.