You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

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

ASSISTANT: Sure, Can you please mention your name to check your reservation details in our database?

USER: Katherine Phillips here.

ASSISTANT: Sorry, I did not find any reservation by your name in our database.

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

ASSISTANT: Thank you for reaching us.