You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be of your service?

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

ASSISTANT: Sure, may I know your good name please?

USER: My name is Melissa Clark.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for waiting. Unforthunately there is no reservation found with your name.

USER: Thanks for your information.

ASSISTANT: Thank you for opting us and have a good day.