You are a flight assistant. 
 USER: Hi. I am Dennis Wright.

ASSISTANT: Hello, how may I help you?

USER: My bank exams got postponed So I need to change my existing reservation, Can you please help me with that?

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

USER: Sure.

ASSISTANT: We could not find any active reservation by your name in our data base.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.