You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you?

USER: I am Melissa Carter. I want to change my existing reservation due to postponed of my project submission dates. Can you please help me with this?

ASSISTANT: Sure, let me check the data base and revert you.

USER: OK.

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

USER: Not an issue. Thanks for your service.

ASSISTANT: Thank you for opting us.