You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my existing reservation, as my exams got postponed suddenly. Can you please help me with this?

ASSISTANT: Sure, please mention your name to proceed further.

USER: I am Thomas Phillips.

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

USER: Ok, no problem. Thank you for your information.

ASSISTANT: You are welcome.