You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to postpone of my exams, can you help me with that?

ASSISTANT: Sure, can you mention your name please?

USER: My name is Margaret Harris.

ASSISTANT: Sorry, no active reservation found on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for contacting us.