You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Gregory Martin. I need to change my existing reservation as my exams got postponed, Can you please help me with that?

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: That's ok, thanks for your assistance.

ASSISTANT: Thank you for reaching us.